{"id":5822,"date":"2022-05-23T23:31:38","date_gmt":"2022-05-23T15:31:38","guid":{"rendered":"https:\/\/damogame.cn:15443\/wordpress\/?p=5822"},"modified":"2022-05-23T23:31:38","modified_gmt":"2022-05-23T15:31:38","slug":"%e4%b8%80%e4%bb%bd%e4%b8%8d%e5%8f%af%e5%a4%9a%e5%be%97%e7%9a%84-ts-%e5%ad%a6%e4%b9%a0%e6%8c%87%e5%8d%97%ef%bc%881-8w%e5%ad%97%ef%bc%89","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/5822","title":{"rendered":"\u4e00\u4efd\u4e0d\u53ef\u591a\u5f97\u7684 TS \u5b66\u4e60\u6307\u5357\uff081.8W\u5b57\uff09"},"content":{"rendered":"<div class=\"author-info-block\" data-v-409ef5ee=\"\">\n<div class=\"author-info-box\" data-v-409ef5ee=\"\">\n<div class=\"meta-box\" data-v-409ef5ee=\"\"><a href=\"https:\/\/juejin.cn\/post\/6872111128135073806\">\u539f\u6587\u5730\u5740<\/a><\/div>\n<div data-v-409ef5ee=\"\"><\/div>\n<\/div>\n<p><button class=\"follow-button follow\" data-v-565dd611=\"\" data-v-409ef5ee=\"\"><span class=\"text\" data-v-565dd611=\"\" data-text=\"\u53d6\u6d88\u5173\u6ce8\">\u5173\u6ce8<\/span><\/button><\/div>\n<p><img decoding=\"async\" class=\"lazy article-hero\" src=\"https:\/\/p1-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/cb8fe2f21686416fab7a2ac94cfea6e2~tplv-k3u1fbpfcp-zoom-crop-mark:1304:1304:1304:734.awebp\" alt=\"\u4e00\u4efd\u4e0d\u53ef\u591a\u5f97\u7684 TS \u5b66\u4e60\u6307\u5357\uff081.8W\u5b57\uff09\" data-v-0808752c=\"\" data-v-409ef5ee=\"\" data-src=\"https:\/\/p1-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/cb8fe2f21686416fab7a2ac94cfea6e2~tplv-k3u1fbpfcp-zoom-crop-mark:1304:1304:1304:734.awebp\" \/><\/p>\n<div class=\"article-content\" data-v-409ef5ee=\"\">\n<div class=\"markdown-body\">\n<p>\u963f\u5b9d\u54e5\u7b2c\u4e00\u6b21\u4f7f\u7528\u00a0<a title=\"https:\/\/www.typescriptlang.org\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fwww.typescriptlang.org%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript<\/a>\u00a0\u662f\u5728 Angular 2.x \u9879\u76ee\u4e2d\uff0c\u90a3\u65f6\u5019 TypeScript \u8fd8\u6ca1\u6709\u8fdb\u5165\u5927\u4f17\u7684\u89c6\u91ce\u3002\u7136\u800c\u73b0\u5728\u5b66\u4e60 TypeScript \u7684\u5c0f\u4f19\u4f34\u8d8a\u6765\u8d8a\u591a\u4e86\uff0c\u672c\u6587\u963f\u5b9d\u54e5\u5c06\u4ece\u00a0<strong>16<\/strong>\u00a0\u4e2a\u65b9\u9762\u5165\u624b\uff0c\u5e26\u4f60\u4e00\u6b65\u6b65\u5b66\u4e60 TypeScript\uff0c\u611f\u5174\u8da3\u7684\u5c0f\u4f19\u4f34\u4e0d\u8981\u9519\u8fc7\u3002<\/p>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p3-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/d88a00458ce14c73bd3114239f5cb7e2~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<h3 data-id=\"heading-0\">\u4e00\u3001TypeScript \u662f\u4ec0\u4e48<\/h3>\n<p><a title=\"https:\/\/www.typescriptlang.org\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fwww.typescriptlang.org%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript<\/a>\u00a0\u662f\u4e00\u79cd\u7531\u5fae\u8f6f\u5f00\u53d1\u7684\u81ea\u7531\u548c\u5f00\u6e90\u7684\u7f16\u7a0b\u8bed\u8a00\u3002\u5b83\u662f JavaScript \u7684\u4e00\u4e2a\u8d85\u96c6\uff0c\u800c\u4e14\u672c\u8d28\u4e0a\u5411\u8fd9\u4e2a\u8bed\u8a00\u6dfb\u52a0\u4e86\u53ef\u9009\u7684\u9759\u6001\u7c7b\u578b\u548c\u57fa\u4e8e\u7c7b\u7684\u9762\u5411\u5bf9\u8c61\u7f16\u7a0b\u3002<\/p>\n<p>TypeScript \u63d0\u4f9b\u6700\u65b0\u7684\u548c\u4e0d\u65ad\u53d1\u5c55\u7684 JavaScript \u7279\u6027\uff0c\u5305\u62ec\u90a3\u4e9b\u6765\u81ea 2015 \u5e74\u7684 ECMAScript \u548c\u672a\u6765\u7684\u63d0\u6848\u4e2d\u7684\u7279\u6027\uff0c\u6bd4\u5982\u5f02\u6b65\u529f\u80fd\u548c Decorators\uff0c\u4ee5\u5e2e\u52a9\u5efa\u7acb\u5065\u58ee\u7684\u7ec4\u4ef6\u3002\u4e0b\u56fe\u663e\u793a\u4e86 TypeScript \u4e0e ES5\u3001ES2015 \u548c ES2016 \u4e4b\u95f4\u7684\u5173\u7cfb\uff1a<\/p>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p1-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/abcaa2a4d7b5416f95091b78492f8d6a~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<h4 data-id=\"heading-1\">1.1 TypeScript \u4e0e JavaScript \u7684\u533a\u522b<\/h4>\n<table>\n<thead>\n<tr>\n<th align=\"center\">TypeScript<\/th>\n<th align=\"center\">JavaScript<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td align=\"center\">JavaScript \u7684\u8d85\u96c6\u7528\u4e8e\u89e3\u51b3\u5927\u578b\u9879\u76ee\u7684\u4ee3\u7801\u590d\u6742\u6027<\/td>\n<td align=\"center\">\u4e00\u79cd\u811a\u672c\u8bed\u8a00\uff0c\u7528\u4e8e\u521b\u5efa\u52a8\u6001\u7f51\u9875<\/td>\n<\/tr>\n<tr>\n<td align=\"center\">\u53ef\u4ee5\u5728\u7f16\u8bd1\u671f\u95f4\u53d1\u73b0\u5e76\u7ea0\u6b63\u9519\u8bef<\/td>\n<td align=\"center\">\u4f5c\u4e3a\u4e00\u79cd\u89e3\u91ca\u578b\u8bed\u8a00\uff0c\u53ea\u80fd\u5728\u8fd0\u884c\u65f6\u53d1\u73b0\u9519\u8bef<\/td>\n<\/tr>\n<tr>\n<td align=\"center\">\u5f3a\u7c7b\u578b\uff0c\u652f\u6301\u9759\u6001\u548c\u52a8\u6001\u7c7b\u578b<\/td>\n<td align=\"center\">\u5f31\u7c7b\u578b\uff0c\u6ca1\u6709\u9759\u6001\u7c7b\u578b\u9009\u9879<\/td>\n<\/tr>\n<tr>\n<td align=\"center\">\u6700\u7ec8\u88ab\u7f16\u8bd1\u6210 JavaScript \u4ee3\u7801\uff0c\u4f7f\u6d4f\u89c8\u5668\u53ef\u4ee5\u7406\u89e3<\/td>\n<td align=\"center\">\u53ef\u4ee5\u76f4\u63a5\u5728\u6d4f\u89c8\u5668\u4e2d\u4f7f\u7528<\/td>\n<\/tr>\n<tr>\n<td align=\"center\">\u652f\u6301\u6a21\u5757\u3001\u6cdb\u578b\u548c\u63a5\u53e3<\/td>\n<td align=\"center\">\u4e0d\u652f\u6301\u6a21\u5757\uff0c\u6cdb\u578b\u6216\u63a5\u53e3<\/td>\n<\/tr>\n<tr>\n<td align=\"center\">\u793e\u533a\u7684\u652f\u6301\u4ecd\u5728\u589e\u957f\uff0c\u800c\u4e14\u8fd8\u4e0d\u662f\u5f88\u5927<\/td>\n<td align=\"center\">\u5927\u91cf\u7684\u793e\u533a\u652f\u6301\u4ee5\u53ca\u5927\u91cf\u6587\u6863\u548c\u89e3\u51b3\u95ee\u9898\u7684\u652f\u6301<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 data-id=\"heading-2\">1.2 \u83b7\u53d6 TypeScript<\/h4>\n<p>\u547d\u4ee4\u884c\u7684 TypeScript \u7f16\u8bd1\u5668\u53ef\u4ee5\u4f7f\u7528\u00a0<a title=\"https:\/\/www.npmjs.com\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fwww.npmjs.com%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">npm<\/a>\u00a0\u5305\u7ba1\u7406\u5668\u6765\u5b89\u88c5\u3002<\/p>\n<h5 data-id=\"heading-3\">1.\u5b89\u88c5 TypeScript<\/h5>\n<pre><code class=\"hljs language-shell copyable\" lang=\"shell\"><span class=\"hljs-meta\">$<\/span><span class=\"bash\"> npm install -g typescript<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-4\">2.\u9a8c\u8bc1 TypeScript<\/h5>\n<pre><code class=\"hljs language-shell copyable\" lang=\"shell\"><span class=\"hljs-meta\">$<\/span><span class=\"bash\"> tsc -v<\/span> \r\n<span class=\"hljs-meta\">#<\/span><span class=\"bash\"> Version 4.0.2<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-5\">3.\u7f16\u8bd1 TypeScript \u6587\u4ef6<\/h5>\n<pre><code class=\"hljs language-shell copyable\" lang=\"shell\"><span class=\"hljs-meta\">$<\/span><span class=\"bash\"> tsc helloworld.ts<\/span>\r\n<span class=\"hljs-meta\">#<\/span><span class=\"bash\"> helloworld.ts =&gt; helloworld.js<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5f53\u7136\uff0c\u5bf9\u521a\u5165\u95e8 TypeScript \u7684\u5c0f\u4f19\u4f34\u6765\u8bf4\uff0c\u4e5f\u53ef\u4ee5\u4e0d\u7528\u5b89\u88c5\u00a0<code>typescript<\/code>\uff0c\u800c\u662f\u76f4\u63a5\u4f7f\u7528\u7ebf\u4e0a\u7684\u00a0<a title=\"https:\/\/www.typescriptlang.org\/play\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fwww.typescriptlang.org%2Fplay%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript Playground<\/a>\u00a0\u6765\u5b66\u4e60\u65b0\u7684\u8bed\u6cd5\u6216\u65b0\u7279\u6027\u3002\u901a\u8fc7\u914d\u7f6e\u00a0<strong>TS Config<\/strong>\u00a0\u7684 Target\uff0c\u53ef\u4ee5\u8bbe\u7f6e\u4e0d\u540c\u7684\u7f16\u8bd1\u76ee\u6807\uff0c\u4ece\u800c\u7f16\u8bd1\u751f\u6210\u4e0d\u540c\u7684\u76ee\u6807\u4ee3\u7801\u3002<\/p>\n<p>\u4e0b\u56fe\u793a\u4f8b\u4e2d\u6240\u8bbe\u7f6e\u7684\u7f16\u8bd1\u76ee\u6807\u662f ES5\uff1a<\/p>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p6-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/5db52f7a4d664d93a72a3da6e6a92ae0~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\uff08\u56fe\u7247\u6765\u6e90\uff1a<a title=\"https:\/\/www.typescriptlang.org\/play%EF%BC%89\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fwww.typescriptlang.org%2Fplay%25EF%25BC%2589\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">www.typescriptlang.org\/play\uff09<\/a><\/p>\n<h4 data-id=\"heading-6\">1.3 \u5178\u578b TypeScript \u5de5\u4f5c\u6d41\u7a0b<\/h4>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p1-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/dea0cbad55b246a8a7e65aec57273ade~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\u5982\u4f60\u6240\u89c1\uff0c\u5728\u4e0a\u56fe\u4e2d\u5305\u542b 3 \u4e2a ts \u6587\u4ef6\uff1aa.ts\u3001b.ts \u548c c.ts\u3002\u8fd9\u4e9b\u6587\u4ef6\u5c06\u88ab TypeScript \u7f16\u8bd1\u5668\uff0c\u6839\u636e\u914d\u7f6e\u7684\u7f16\u8bd1\u9009\u9879\u7f16\u8bd1\u6210 3 \u4e2a js \u6587\u4ef6\uff0c\u5373 a.js\u3001b.js \u548c c.js\u3002\u5bf9\u4e8e\u5927\u591a\u6570\u4f7f\u7528 TypeScript \u5f00\u53d1\u7684 Web \u9879\u76ee\uff0c\u6211\u4eec\u8fd8\u4f1a\u5bf9\u7f16\u8bd1\u751f\u6210\u7684 js \u6587\u4ef6\u8fdb\u884c\u6253\u5305\u5904\u7406\uff0c\u7136\u540e\u5728\u8fdb\u884c\u90e8\u7f72\u3002<\/p>\n<h4 data-id=\"heading-7\">1.4 TypeScript \u521d\u4f53\u9a8c<\/h4>\n<p>\u65b0\u5efa\u4e00\u4e2a\u00a0<code>hello.ts<\/code>\u00a0\u6587\u4ef6\uff0c\u5e76\u8f93\u5165\u4ee5\u4e0b\u5185\u5bb9\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">greet<\/span>(<span class=\"hljs-params\">person: <span class=\"hljs-built_in\">string<\/span><\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-string\">'Hello, '<\/span> + person;\r\n}\r\n\r\n<span class=\"hljs-built_in\">console<\/span>.log(greet(<span class=\"hljs-string\">\"TypeScript\"<\/span>));\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u7136\u540e\u6267\u884c\u00a0<code>tsc hello.ts<\/code>\u00a0\u547d\u4ee4\uff0c\u4e4b\u540e\u4f1a\u751f\u6210\u4e00\u4e2a\u7f16\u8bd1\u597d\u7684\u6587\u4ef6\u00a0<code>hello.js<\/code>\uff1a<\/p>\n<pre><code class=\"hljs language-javascript copyable\" lang=\"javascript\"><span class=\"hljs-meta\">\"use strict\"<\/span>;\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">greet<\/span>(<span class=\"hljs-params\">person<\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-string\">'Hello, '<\/span> + person;\r\n}\r\n<span class=\"hljs-built_in\">console<\/span>.log(greet(<span class=\"hljs-string\">\"TypeScript\"<\/span>));\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u89c2\u5bdf\u4ee5\u4e0a\u7f16\u8bd1\u540e\u7684\u8f93\u51fa\u7ed3\u679c\uff0c\u6211\u4eec\u53d1\u73b0\u00a0<code>person<\/code>\u00a0\u53c2\u6570\u7684\u7c7b\u578b\u4fe1\u606f\u5728\u7f16\u8bd1\u540e\u88ab\u64e6\u9664\u4e86\u3002TypeScript \u53ea\u4f1a\u5728\u7f16\u8bd1\u9636\u6bb5\u5bf9\u7c7b\u578b\u8fdb\u884c\u9759\u6001\u68c0\u67e5\uff0c\u5982\u679c\u53d1\u73b0\u6709\u9519\u8bef\uff0c\u7f16\u8bd1\u65f6\u5c31\u4f1a\u62a5\u9519\u3002\u800c\u5728\u8fd0\u884c\u65f6\uff0c\u7f16\u8bd1\u751f\u6210\u7684 JS \u4e0e\u666e\u901a\u7684 JavaScript \u6587\u4ef6\u4e00\u6837\uff0c\u5e76\u4e0d\u4f1a\u8fdb\u884c\u7c7b\u578b\u68c0\u67e5\u3002<\/p>\n<h3 data-id=\"heading-8\">\u4e8c\u3001TypeScript \u57fa\u7840\u7c7b\u578b<\/h3>\n<h4 data-id=\"heading-9\">2.1 Boolean \u7c7b\u578b<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> isDone: <span class=\"hljs-built_in\">boolean<\/span> = <span class=\"hljs-literal\">false<\/span>;\r\n<span class=\"hljs-comment\">\/\/ ES5\uff1avar isDone = false;<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-10\">2.2 Number \u7c7b\u578b<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> count: <span class=\"hljs-built_in\">number<\/span> = <span class=\"hljs-number\">10<\/span>;\r\n<span class=\"hljs-comment\">\/\/ ES5\uff1avar count = 10;<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-11\">2.3 String \u7c7b\u578b<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> name: <span class=\"hljs-built_in\">string<\/span> = <span class=\"hljs-string\">\"semliker\"<\/span>;\r\n<span class=\"hljs-comment\">\/\/ ES5\uff1avar name = 'semlinker';<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-12\">2.4 Symbol \u7c7b\u578b<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">const<\/span> sym = <span class=\"hljs-built_in\">Symbol<\/span>();\r\n<span class=\"hljs-keyword\">let<\/span> obj = {\r\n  [sym]: <span class=\"hljs-string\">\"semlinker\"<\/span>,\r\n};\r\n\r\n<span class=\"hljs-built_in\">console<\/span>.log(obj[sym]); <span class=\"hljs-comment\">\/\/ semlinker <\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-13\">2.5 Array \u7c7b\u578b<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> list: <span class=\"hljs-built_in\">number<\/span>[] = [<span class=\"hljs-number\">1<\/span>, <span class=\"hljs-number\">2<\/span>, <span class=\"hljs-number\">3<\/span>];\r\n<span class=\"hljs-comment\">\/\/ ES5\uff1avar list = [1,2,3];<\/span>\r\n\r\n<span class=\"hljs-keyword\">let<\/span> list: <span class=\"hljs-built_in\">Array<\/span>&lt;<span class=\"hljs-built_in\">number<\/span>&gt; = [<span class=\"hljs-number\">1<\/span>, <span class=\"hljs-number\">2<\/span>, <span class=\"hljs-number\">3<\/span>]; <span class=\"hljs-comment\">\/\/ Array&lt;number&gt;\u6cdb\u578b\u8bed\u6cd5<\/span>\r\n<span class=\"hljs-comment\">\/\/ ES5\uff1avar list = [1,2,3];<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-14\">2.6 Enum \u7c7b\u578b<\/h4>\n<p>\u4f7f\u7528\u679a\u4e3e\u6211\u4eec\u53ef\u4ee5\u5b9a\u4e49\u4e00\u4e9b\u5e26\u540d\u5b57\u7684\u5e38\u91cf\u3002 \u4f7f\u7528\u679a\u4e3e\u53ef\u4ee5\u6e05\u6670\u5730\u8868\u8fbe\u610f\u56fe\u6216\u521b\u5efa\u4e00\u7ec4\u6709\u533a\u522b\u7684\u7528\u4f8b\u3002 TypeScript \u652f\u6301\u6570\u5b57\u7684\u548c\u57fa\u4e8e\u5b57\u7b26\u4e32\u7684\u679a\u4e3e\u3002<\/p>\n<h5 data-id=\"heading-15\">1.\u6570\u5b57\u679a\u4e3e<\/h5>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-built_in\">enum<\/span> Direction {\r\n  NORTH,\r\n  SOUTH,\r\n  EAST,\r\n  WEST,\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> dir: Direction = Direction.NORTH;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0cNORTH \u7684\u521d\u59cb\u503c\u4e3a 0\uff0c\u5176\u4f59\u7684\u6210\u5458\u4f1a\u4ece 1 \u5f00\u59cb\u81ea\u52a8\u589e\u957f\u3002\u6362\u53e5\u8bdd\u8bf4\uff0cDirection.SOUTH \u7684\u503c\u4e3a 1\uff0cDirection.EAST \u7684\u503c\u4e3a 2\uff0cDirection.WEST \u7684\u503c\u4e3a 3\u3002<\/p>\n<p>\u4ee5\u4e0a\u7684\u679a\u4e3e\u793a\u4f8b\u7ecf\u7f16\u8bd1\u540e\uff0c\u5bf9\u5e94\u7684 ES5 \u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-javascript copyable\" lang=\"javascript\"><span class=\"hljs-meta\">\"use strict\"<\/span>;\r\n<span class=\"hljs-keyword\">var<\/span> Direction;\r\n(<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (<span class=\"hljs-params\">Direction<\/span>) <\/span>{\r\n  Direction[(Direction[<span class=\"hljs-string\">\"NORTH\"<\/span>] = <span class=\"hljs-number\">0<\/span>)] = <span class=\"hljs-string\">\"NORTH\"<\/span>;\r\n  Direction[(Direction[<span class=\"hljs-string\">\"SOUTH\"<\/span>] = <span class=\"hljs-number\">1<\/span>)] = <span class=\"hljs-string\">\"SOUTH\"<\/span>;\r\n  Direction[(Direction[<span class=\"hljs-string\">\"EAST\"<\/span>] = <span class=\"hljs-number\">2<\/span>)] = <span class=\"hljs-string\">\"EAST\"<\/span>;\r\n  Direction[(Direction[<span class=\"hljs-string\">\"WEST\"<\/span>] = <span class=\"hljs-number\">3<\/span>)] = <span class=\"hljs-string\">\"WEST\"<\/span>;\r\n})(Direction || (Direction = {}));\r\n<span class=\"hljs-keyword\">var<\/span> dir = Direction.NORTH;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5f53\u7136\u6211\u4eec\u4e5f\u53ef\u4ee5\u8bbe\u7f6e NORTH \u7684\u521d\u59cb\u503c\uff0c\u6bd4\u5982\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-built_in\">enum<\/span> Direction {\r\n  NORTH = <span class=\"hljs-number\">3<\/span>,\r\n  SOUTH,\r\n  EAST,\r\n  WEST,\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-16\">2.\u5b57\u7b26\u4e32\u679a\u4e3e<\/h5>\n<p>\u5728 TypeScript 2.4 \u7248\u672c\uff0c\u5141\u8bb8\u6211\u4eec\u4f7f\u7528\u5b57\u7b26\u4e32\u679a\u4e3e\u3002\u5728\u4e00\u4e2a\u5b57\u7b26\u4e32\u679a\u4e3e\u91cc\uff0c\u6bcf\u4e2a\u6210\u5458\u90fd\u5fc5\u987b\u7528\u5b57\u7b26\u4e32\u5b57\u9762\u91cf\uff0c\u6216\u53e6\u5916\u4e00\u4e2a\u5b57\u7b26\u4e32\u679a\u4e3e\u6210\u5458\u8fdb\u884c\u521d\u59cb\u5316\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-built_in\">enum<\/span> Direction {\r\n  NORTH = <span class=\"hljs-string\">\"NORTH\"<\/span>,\r\n  SOUTH = <span class=\"hljs-string\">\"SOUTH\"<\/span>,\r\n  EAST = <span class=\"hljs-string\">\"EAST\"<\/span>,\r\n  WEST = <span class=\"hljs-string\">\"WEST\"<\/span>,\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a\u4ee3\u7801\u5bf9\u5e94\u7684 ES5 \u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-meta\">\"use strict\"<\/span>;\r\n<span class=\"hljs-keyword\">var<\/span> Direction;\r\n(<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (<span class=\"hljs-params\">Direction<\/span>) <\/span>{\r\n    Direction[<span class=\"hljs-string\">\"NORTH\"<\/span>] = <span class=\"hljs-string\">\"NORTH\"<\/span>;\r\n    Direction[<span class=\"hljs-string\">\"SOUTH\"<\/span>] = <span class=\"hljs-string\">\"SOUTH\"<\/span>;\r\n    Direction[<span class=\"hljs-string\">\"EAST\"<\/span>] = <span class=\"hljs-string\">\"EAST\"<\/span>;\r\n    Direction[<span class=\"hljs-string\">\"WEST\"<\/span>] = <span class=\"hljs-string\">\"WEST\"<\/span>;\r\n})(Direction || (Direction = {}));\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u901a\u8fc7\u89c2\u5bdf\u6570\u5b57\u679a\u4e3e\u548c\u5b57\u7b26\u4e32\u679a\u4e3e\u7684\u7f16\u8bd1\u7ed3\u679c\uff0c\u6211\u4eec\u53ef\u4ee5\u77e5\u9053\u6570\u5b57\u679a\u4e3e\u9664\u4e86\u652f\u6301\u00a0<strong>\u4ece\u6210\u5458\u540d\u79f0\u5230\u6210\u5458\u503c<\/strong>\u00a0\u7684\u666e\u901a\u6620\u5c04\u4e4b\u5916\uff0c\u5b83\u8fd8\u652f\u6301\u00a0<strong>\u4ece\u6210\u5458\u503c\u5230\u6210\u5458\u540d\u79f0<\/strong>\u00a0\u7684\u53cd\u5411\u6620\u5c04\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-built_in\">enum<\/span> Direction {\r\n  NORTH,\r\n  SOUTH,\r\n  EAST,\r\n  WEST,\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> dirName = Direction[<span class=\"hljs-number\">0<\/span>]; <span class=\"hljs-comment\">\/\/ NORTH<\/span>\r\n<span class=\"hljs-keyword\">let<\/span> dirVal = Direction[<span class=\"hljs-string\">\"NORTH\"<\/span>]; <span class=\"hljs-comment\">\/\/ 0<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u53e6\u5916\uff0c\u5bf9\u4e8e\u7eaf\u5b57\u7b26\u4e32\u679a\u4e3e\uff0c\u6211\u4eec\u4e0d\u80fd\u7701\u7565\u4efb\u4f55\u521d\u59cb\u5316\u7a0b\u5e8f\u3002\u800c\u6570\u5b57\u679a\u4e3e\u5982\u679c\u6ca1\u6709\u663e\u5f0f\u8bbe\u7f6e\u503c\u65f6\uff0c\u5219\u4f1a\u4f7f\u7528\u9ed8\u8ba4\u89c4\u5219\u8fdb\u884c\u521d\u59cb\u5316\u3002<\/p>\n<h5 data-id=\"heading-17\">3.\u5e38\u91cf\u679a\u4e3e<\/h5>\n<p>\u9664\u4e86\u6570\u5b57\u679a\u4e3e\u548c\u5b57\u7b26\u4e32\u679a\u4e3e\u4e4b\u5916\uff0c\u8fd8\u6709\u4e00\u79cd\u7279\u6b8a\u7684\u679a\u4e3e \u2014\u2014 \u5e38\u91cf\u679a\u4e3e\u3002\u5b83\u662f\u4f7f\u7528\u00a0<code>const<\/code>\u00a0\u5173\u952e\u5b57\u4fee\u9970\u7684\u679a\u4e3e\uff0c\u5e38\u91cf\u679a\u4e3e\u4f1a\u4f7f\u7528\u5185\u8054\u8bed\u6cd5\uff0c\u4e0d\u4f1a\u4e3a\u679a\u4e3e\u7c7b\u578b\u7f16\u8bd1\u751f\u6210\u4efb\u4f55 JavaScript\u3002\u4e3a\u4e86\u66f4\u597d\u5730\u7406\u89e3\u8fd9\u53e5\u8bdd\uff0c\u6211\u4eec\u6765\u770b\u4e00\u4e2a\u5177\u4f53\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">const<\/span> <span class=\"hljs-built_in\">enum<\/span> Direction {\r\n  NORTH,\r\n  SOUTH,\r\n  EAST,\r\n  WEST,\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> dir: Direction = Direction.NORTH;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a\u4ee3\u7801\u5bf9\u5e94\u7684 ES5 \u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-javascript copyable\" lang=\"javascript\"><span class=\"hljs-meta\">\"use strict\"<\/span>;\r\n<span class=\"hljs-keyword\">var<\/span> dir = <span class=\"hljs-number\">0<\/span> <span class=\"hljs-comment\">\/* NORTH *\/<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-18\">4.\u5f02\u6784\u679a\u4e3e<\/h5>\n<p>\u5f02\u6784\u679a\u4e3e\u7684\u6210\u5458\u503c\u662f\u6570\u5b57\u548c\u5b57\u7b26\u4e32\u7684\u6df7\u5408\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-built_in\">enum<\/span> Enum {\r\n  A,\r\n  B,\r\n  C = <span class=\"hljs-string\">\"C\"<\/span>,\r\n  D = <span class=\"hljs-string\">\"D\"<\/span>,\r\n  E = <span class=\"hljs-number\">8<\/span>,\r\n  F,\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a\u4ee3\u7801\u5bf9\u4e8e\u7684 ES5 \u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-meta\">\"use strict\"<\/span>;\r\n<span class=\"hljs-keyword\">var<\/span> Enum;\r\n(<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (<span class=\"hljs-params\">Enum<\/span>) <\/span>{\r\n    Enum[Enum[<span class=\"hljs-string\">\"A\"<\/span>] = <span class=\"hljs-number\">0<\/span>] = <span class=\"hljs-string\">\"A\"<\/span>;\r\n    Enum[Enum[<span class=\"hljs-string\">\"B\"<\/span>] = <span class=\"hljs-number\">1<\/span>] = <span class=\"hljs-string\">\"B\"<\/span>;\r\n    Enum[<span class=\"hljs-string\">\"C\"<\/span>] = <span class=\"hljs-string\">\"C\"<\/span>;\r\n    Enum[<span class=\"hljs-string\">\"D\"<\/span>] = <span class=\"hljs-string\">\"D\"<\/span>;\r\n    Enum[Enum[<span class=\"hljs-string\">\"E\"<\/span>] = <span class=\"hljs-number\">8<\/span>] = <span class=\"hljs-string\">\"E\"<\/span>;\r\n    Enum[Enum[<span class=\"hljs-string\">\"F\"<\/span>] = <span class=\"hljs-number\">9<\/span>] = <span class=\"hljs-string\">\"F\"<\/span>;\r\n})(Enum || (Enum = {}));\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u901a\u8fc7\u89c2\u5bdf\u4e0a\u8ff0\u751f\u6210\u7684 ES5 \u4ee3\u7801\uff0c\u6211\u4eec\u53ef\u4ee5\u53d1\u73b0\u6570\u5b57\u679a\u4e3e\u76f8\u5bf9\u5b57\u7b26\u4e32\u679a\u4e3e\u591a\u4e86 \u201c\u53cd\u5411\u6620\u5c04\u201d\uff1a<\/p>\n<pre><code class=\"hljs language-javascript copyable\" lang=\"javascript\"><span class=\"hljs-built_in\">console<\/span>.log(Enum.A) <span class=\"hljs-comment\">\/\/\u8f93\u51fa\uff1a0<\/span>\r\n<span class=\"hljs-built_in\">console<\/span>.log(Enum[<span class=\"hljs-number\">0<\/span>]) <span class=\"hljs-comment\">\/\/ \u8f93\u51fa\uff1aA<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-19\">2.7 Any \u7c7b\u578b<\/h4>\n<p>\u5728 TypeScript \u4e2d\uff0c\u4efb\u4f55\u7c7b\u578b\u90fd\u53ef\u4ee5\u88ab\u5f52\u4e3a any \u7c7b\u578b\u3002\u8fd9\u8ba9 any \u7c7b\u578b\u6210\u4e3a\u4e86\u7c7b\u578b\u7cfb\u7edf\u7684\u9876\u7ea7\u7c7b\u578b\uff08\u4e5f\u88ab\u79f0\u4f5c\u5168\u5c40\u8d85\u7ea7\u7c7b\u578b\uff09\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> notSure: <span class=\"hljs-built_in\">any<\/span> = <span class=\"hljs-number\">666<\/span>;\r\nnotSure = <span class=\"hljs-string\">\"semlinker\"<\/span>;\r\nnotSure = <span class=\"hljs-literal\">false<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><code>any<\/code>\u00a0\u7c7b\u578b\u672c\u8d28\u4e0a\u662f\u7c7b\u578b\u7cfb\u7edf\u7684\u4e00\u4e2a\u9003\u9038\u8231\u3002\u4f5c\u4e3a\u5f00\u53d1\u8005\uff0c\u8fd9\u7ed9\u4e86\u6211\u4eec\u5f88\u5927\u7684\u81ea\u7531\uff1aTypeScript \u5141\u8bb8\u6211\u4eec\u5bf9\u00a0<code>any<\/code>\u00a0\u7c7b\u578b\u7684\u503c\u6267\u884c\u4efb\u4f55\u64cd\u4f5c\uff0c\u800c\u65e0\u9700\u4e8b\u5148\u6267\u884c\u4efb\u4f55\u5f62\u5f0f\u7684\u68c0\u67e5\u3002\u6bd4\u5982\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> value: <span class=\"hljs-built_in\">any<\/span>;\r\n\r\nvalue.foo.bar; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue.trim(); <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue(); <span class=\"hljs-comment\">\/\/ OK<\/span>\r\n<span class=\"hljs-keyword\">new<\/span> value(); <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue[<span class=\"hljs-number\">0<\/span>][<span class=\"hljs-number\">1<\/span>]; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u8bb8\u591a\u573a\u666f\u4e0b\uff0c\u8fd9\u592a\u5bbd\u677e\u4e86\u3002\u4f7f\u7528\u00a0<code>any<\/code>\u00a0\u7c7b\u578b\uff0c\u53ef\u4ee5\u5f88\u5bb9\u6613\u5730\u7f16\u5199\u7c7b\u578b\u6b63\u786e\u4f46\u5728\u8fd0\u884c\u65f6\u6709\u95ee\u9898\u7684\u4ee3\u7801\u3002\u5982\u679c\u6211\u4eec\u4f7f\u7528\u00a0<code>any<\/code>\u00a0\u7c7b\u578b\uff0c\u5c31\u65e0\u6cd5\u4f7f\u7528 TypeScript \u63d0\u4f9b\u7684\u5927\u91cf\u7684\u4fdd\u62a4\u673a\u5236\u3002\u4e3a\u4e86\u89e3\u51b3\u00a0<code>any<\/code>\u00a0\u5e26\u6765\u7684\u95ee\u9898\uff0cTypeScript 3.0 \u5f15\u5165\u4e86\u00a0<code>unknown<\/code>\u00a0\u7c7b\u578b\u3002<\/p>\n<h4 data-id=\"heading-20\">2.8 Unknown \u7c7b\u578b<\/h4>\n<p>\u5c31\u50cf\u6240\u6709\u7c7b\u578b\u90fd\u53ef\u4ee5\u8d4b\u503c\u7ed9\u00a0<code>any<\/code>\uff0c\u6240\u6709\u7c7b\u578b\u4e5f\u90fd\u53ef\u4ee5\u8d4b\u503c\u7ed9\u00a0<code>unknown<\/code>\u3002\u8fd9\u4f7f\u5f97\u00a0<code>unknown<\/code>\u00a0\u6210\u4e3a TypeScript \u7c7b\u578b\u7cfb\u7edf\u7684\u53e6\u4e00\u79cd\u9876\u7ea7\u7c7b\u578b\uff08\u53e6\u4e00\u79cd\u662f\u00a0<code>any<\/code>\uff09\u3002\u4e0b\u9762\u6211\u4eec\u6765\u770b\u4e00\u4e0b\u00a0<code>unknown<\/code>\u00a0\u7c7b\u578b\u7684\u4f7f\u7528\u793a\u4f8b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> value: unknown;\r\n\r\nvalue = <span class=\"hljs-literal\">true<\/span>; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue = <span class=\"hljs-number\">42<\/span>; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue = <span class=\"hljs-string\">\"Hello World\"<\/span>; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue = []; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue = {}; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue = <span class=\"hljs-built_in\">Math<\/span>.random; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue = <span class=\"hljs-literal\">null<\/span>; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue = <span class=\"hljs-literal\">undefined<\/span>; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue = <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-built_in\">TypeError<\/span>(); <span class=\"hljs-comment\">\/\/ OK<\/span>\r\nvalue = <span class=\"hljs-built_in\">Symbol<\/span>(<span class=\"hljs-string\">\"type\"<\/span>); <span class=\"hljs-comment\">\/\/ OK<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5bf9\u00a0<code>value<\/code>\u00a0\u53d8\u91cf\u7684\u6240\u6709\u8d4b\u503c\u90fd\u88ab\u8ba4\u4e3a\u662f\u7c7b\u578b\u6b63\u786e\u7684\u3002\u4f46\u662f\uff0c\u5f53\u6211\u4eec\u5c1d\u8bd5\u5c06\u7c7b\u578b\u4e3a\u00a0<code>unknown<\/code>\u00a0\u7684\u503c\u8d4b\u503c\u7ed9\u5176\u4ed6\u7c7b\u578b\u7684\u53d8\u91cf\u65f6\u4f1a\u53d1\u751f\u4ec0\u4e48\uff1f<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> value: unknown;\r\n\r\n<span class=\"hljs-keyword\">let<\/span> value1: unknown = value; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\n<span class=\"hljs-keyword\">let<\/span> value2: <span class=\"hljs-built_in\">any<\/span> = value; <span class=\"hljs-comment\">\/\/ OK<\/span>\r\n<span class=\"hljs-keyword\">let<\/span> value3: <span class=\"hljs-built_in\">boolean<\/span> = value; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"hljs-keyword\">let<\/span> value4: <span class=\"hljs-built_in\">number<\/span> = value; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"hljs-keyword\">let<\/span> value5: <span class=\"hljs-built_in\">string<\/span> = value; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"hljs-keyword\">let<\/span> value6: <span class=\"hljs-built_in\">object<\/span> = value; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"hljs-keyword\">let<\/span> value7: <span class=\"hljs-built_in\">any<\/span>[] = value; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"hljs-keyword\">let<\/span> value8: <span class=\"hljs-built_in\">Function<\/span> = value; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><code>unknown<\/code>\u00a0\u7c7b\u578b\u53ea\u80fd\u88ab\u8d4b\u503c\u7ed9\u00a0<code>any<\/code>\u00a0\u7c7b\u578b\u548c\u00a0<code>unknown<\/code>\u00a0\u7c7b\u578b\u672c\u8eab\u3002\u76f4\u89c2\u5730\u8bf4\uff0c\u8fd9\u662f\u6709\u9053\u7406\u7684\uff1a\u53ea\u6709\u80fd\u591f\u4fdd\u5b58\u4efb\u610f\u7c7b\u578b\u503c\u7684\u5bb9\u5668\u624d\u80fd\u4fdd\u5b58\u00a0<code>unknown<\/code>\u00a0\u7c7b\u578b\u7684\u503c\u3002\u6bd5\u7adf\u6211\u4eec\u4e0d\u77e5\u9053\u53d8\u91cf\u00a0<code>value<\/code>\u00a0\u4e2d\u5b58\u50a8\u4e86\u4ec0\u4e48\u7c7b\u578b\u7684\u503c\u3002<\/p>\n<p>\u73b0\u5728\u8ba9\u6211\u4eec\u770b\u770b\u5f53\u6211\u4eec\u5c1d\u8bd5\u5bf9\u7c7b\u578b\u4e3a\u00a0<code>unknown<\/code>\u00a0\u7684\u503c\u6267\u884c\u64cd\u4f5c\u65f6\u4f1a\u53d1\u751f\u4ec0\u4e48\u3002\u4ee5\u4e0b\u662f\u6211\u4eec\u5728\u4e4b\u524d\u00a0<code>any<\/code>\u00a0\u7ae0\u8282\u770b\u8fc7\u7684\u76f8\u540c\u64cd\u4f5c\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> value: unknown;\r\n\r\nvalue.foo.bar; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\nvalue.trim(); <span class=\"hljs-comment\">\/\/ Error<\/span>\r\nvalue(); <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"hljs-keyword\">new<\/span> value(); <span class=\"hljs-comment\">\/\/ Error<\/span>\r\nvalue[<span class=\"hljs-number\">0<\/span>][<span class=\"hljs-number\">1<\/span>]; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5c06\u00a0<code>value<\/code>\u00a0\u53d8\u91cf\u7c7b\u578b\u8bbe\u7f6e\u4e3a\u00a0<code>unknown<\/code>\u00a0\u540e\uff0c\u8fd9\u4e9b\u64cd\u4f5c\u90fd\u4e0d\u518d\u88ab\u8ba4\u4e3a\u662f\u7c7b\u578b\u6b63\u786e\u7684\u3002\u901a\u8fc7\u5c06\u00a0<code>any<\/code>\u00a0\u7c7b\u578b\u6539\u53d8\u4e3a\u00a0<code>unknown<\/code>\u00a0\u7c7b\u578b\uff0c\u6211\u4eec\u5df2\u5c06\u5141\u8bb8\u6240\u6709\u66f4\u6539\u7684\u9ed8\u8ba4\u8bbe\u7f6e\uff0c\u66f4\u6539\u4e3a\u7981\u6b62\u4efb\u4f55\u66f4\u6539\u3002<\/p>\n<h4 data-id=\"heading-21\">2.9 Tuple \u7c7b\u578b<\/h4>\n<p><strong>\u4f17\u6240\u5468\u77e5\uff0c\u6570\u7ec4\u4e00\u822c\u7531\u540c\u79cd\u7c7b\u578b\u7684\u503c\u7ec4\u6210\uff0c\u4f46\u6709\u65f6\u6211\u4eec\u9700\u8981\u5728\u5355\u4e2a\u53d8\u91cf\u4e2d\u5b58\u50a8\u4e0d\u540c\u7c7b\u578b\u7684\u503c\uff0c\u8fd9\u65f6\u5019\u6211\u4eec\u5c31\u53ef\u4ee5\u4f7f\u7528\u5143\u7ec4<\/strong>\u3002\u5728 JavaScript \u4e2d\u662f\u6ca1\u6709\u5143\u7ec4\u7684\uff0c\u5143\u7ec4\u662f TypeScript \u4e2d\u7279\u6709\u7684\u7c7b\u578b\uff0c\u5176\u5de5\u4f5c\u65b9\u5f0f\u7c7b\u4f3c\u4e8e\u6570\u7ec4\u3002<\/p>\n<p>\u5143\u7ec4\u53ef\u7528\u4e8e\u5b9a\u4e49\u5177\u6709\u6709\u9650\u6570\u91cf\u7684\u672a\u547d\u540d\u5c5e\u6027\u7684\u7c7b\u578b\u3002\u6bcf\u4e2a\u5c5e\u6027\u90fd\u6709\u4e00\u4e2a\u5173\u8054\u7684\u7c7b\u578b\u3002\u4f7f\u7528\u5143\u7ec4\u65f6\uff0c\u5fc5\u987b\u63d0\u4f9b\u6bcf\u4e2a\u5c5e\u6027\u7684\u503c\u3002\u4e3a\u4e86\u66f4\u76f4\u89c2\u5730\u7406\u89e3\u5143\u7ec4\u7684\u6982\u5ff5\uff0c\u6211\u4eec\u6765\u770b\u4e00\u4e2a\u5177\u4f53\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> tupleType: [<span class=\"hljs-built_in\">string<\/span>, <span class=\"hljs-built_in\">boolean<\/span>];\r\ntupleType = [<span class=\"hljs-string\">\"semlinker\"<\/span>, <span class=\"hljs-literal\">true<\/span>];\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u4e0a\u9762\u4ee3\u7801\u4e2d\uff0c\u6211\u4eec\u5b9a\u4e49\u4e86\u4e00\u4e2a\u540d\u4e3a\u00a0<code>tupleType<\/code>\u00a0\u7684\u53d8\u91cf\uff0c\u5b83\u7684\u7c7b\u578b\u662f\u4e00\u4e2a\u7c7b\u578b\u6570\u7ec4\u00a0<code>[string, boolean]<\/code>\uff0c\u7136\u540e\u6211\u4eec\u6309\u7167\u6b63\u786e\u7684\u7c7b\u578b\u4f9d\u6b21\u521d\u59cb\u5316 tupleType \u53d8\u91cf\u3002\u4e0e\u6570\u7ec4\u4e00\u6837\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u4e0b\u6807\u6765\u8bbf\u95ee\u5143\u7ec4\u4e2d\u7684\u5143\u7d20\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-built_in\">console<\/span>.log(tupleType[<span class=\"hljs-number\">0<\/span>]); <span class=\"hljs-comment\">\/\/ semlinker<\/span>\r\n<span class=\"hljs-built_in\">console<\/span>.log(tupleType[<span class=\"hljs-number\">1<\/span>]); <span class=\"hljs-comment\">\/\/ true<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u5143\u7ec4\u521d\u59cb\u5316\u7684\u65f6\u5019\uff0c\u5982\u679c\u51fa\u73b0\u7c7b\u578b\u4e0d\u5339\u914d\u7684\u8bdd\uff0c\u6bd4\u5982\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\">tupleType = [<span class=\"hljs-literal\">true<\/span>, <span class=\"hljs-string\">\"semlinker\"<\/span>];\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u6b64\u65f6\uff0cTypeScript \u7f16\u8bd1\u5668\u4f1a\u63d0\u793a\u4ee5\u4e0b\u9519\u8bef\u4fe1\u606f\uff1a<\/p>\n<pre><code class=\"copyable\">[0]: Type 'true' is not assignable to type 'string'.\r\n[1]: Type 'string' is not assignable to type 'boolean'.\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5f88\u660e\u663e\u662f\u56e0\u4e3a\u7c7b\u578b\u4e0d\u5339\u914d\u5bfc\u81f4\u7684\u3002\u5728\u5143\u7ec4\u521d\u59cb\u5316\u7684\u65f6\u5019\uff0c\u6211\u4eec\u8fd8\u5fc5\u987b\u63d0\u4f9b\u6bcf\u4e2a\u5c5e\u6027\u7684\u503c\uff0c\u4e0d\u7136\u4e5f\u4f1a\u51fa\u73b0\u9519\u8bef\uff0c\u6bd4\u5982\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\">tupleType = [<span class=\"hljs-string\">\"semlinker\"<\/span>];\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u6b64\u65f6\uff0cTypeScript \u7f16\u8bd1\u5668\u4f1a\u63d0\u793a\u4ee5\u4e0b\u9519\u8bef\u4fe1\u606f\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\">Property <span class=\"hljs-string\">'1'<\/span> is missing <span class=\"hljs-keyword\">in<\/span> <span class=\"hljs-keyword\">type<\/span> <span class=\"hljs-string\">'[string]'<\/span> but required <span class=\"hljs-keyword\">in<\/span> <span class=\"hljs-keyword\">type<\/span> <span class=\"hljs-string\">'[string, boolean]'<\/span>.\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-22\">2.10 Void \u7c7b\u578b<\/h4>\n<p>\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u6765\u8bf4\uff0cvoid \u7c7b\u578b\u50cf\u662f\u4e0e any \u7c7b\u578b\u76f8\u53cd\uff0c\u5b83\u8868\u793a\u6ca1\u6709\u4efb\u4f55\u7c7b\u578b\u3002\u5f53\u4e00\u4e2a\u51fd\u6570\u6ca1\u6709\u8fd4\u56de\u503c\u65f6\uff0c\u4f60\u901a\u5e38\u4f1a\u89c1\u5230\u5176\u8fd4\u56de\u503c\u7c7b\u578b\u662f void\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ \u58f0\u660e\u51fd\u6570\u8fd4\u56de\u503c\u4e3avoid<\/span>\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">warnUser<\/span>(): <span class=\"hljs-title\">void<\/span> <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"This is my warning message\"<\/span>);\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a\u4ee3\u7801\u7f16\u8bd1\u751f\u6210\u7684 ES5 \u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-meta\">\"use strict\"<\/span>;\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">warnUser<\/span>() <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"This is my warning message\"<\/span>);\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u58f0\u660e\u4e00\u4e2a void \u7c7b\u578b\u7684\u53d8\u91cf\u6ca1\u6709\u4ec0\u4e48\u4f5c\u7528\uff0c\u56e0\u4e3a\u5728\u4e25\u683c\u6a21\u5f0f\u4e0b\uff0c\u5b83\u7684\u503c\u53ea\u80fd\u4e3a\u00a0<code>undefined<\/code>\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> unusable: <span class=\"hljs-built_in\">void<\/span> = <span class=\"hljs-literal\">undefined<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-23\">2.11 Null \u548c Undefined \u7c7b\u578b<\/h4>\n<p>TypeScript \u91cc\uff0c<code>undefined<\/code>\u00a0\u548c\u00a0<code>null<\/code>\u00a0\u4e24\u8005\u6709\u5404\u81ea\u7684\u7c7b\u578b\u5206\u522b\u4e3a\u00a0<code>undefined<\/code>\u00a0\u548c\u00a0<code>null<\/code>\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> u: <span class=\"hljs-literal\">undefined<\/span> = <span class=\"hljs-literal\">undefined<\/span>;\r\n<span class=\"hljs-keyword\">let<\/span> n: <span class=\"hljs-literal\">null<\/span> = <span class=\"hljs-literal\">null<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-24\">2.12 object, Object \u548c {} \u7c7b\u578b<\/h4>\n<h5 data-id=\"heading-25\">1.object \u7c7b\u578b<\/h5>\n<p>object \u7c7b\u578b\u662f\uff1aTypeScript 2.2 \u5f15\u5165\u7684\u65b0\u7c7b\u578b\uff0c\u5b83\u7528\u4e8e\u8868\u793a\u975e\u539f\u59cb\u7c7b\u578b\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ node_modules\/typescript\/lib\/lib.es5.d.ts<\/span>\r\n<span class=\"hljs-keyword\">interface<\/span> ObjectConstructor {\r\n  create(o: <span class=\"hljs-built_in\">object<\/span> | <span class=\"hljs-literal\">null<\/span>): <span class=\"hljs-built_in\">any<\/span>;\r\n  <span class=\"hljs-comment\">\/\/ ...<\/span>\r\n}\r\n\r\n<span class=\"hljs-keyword\">const<\/span> proto = {};\r\n\r\n<span class=\"hljs-built_in\">Object<\/span>.create(proto);     <span class=\"hljs-comment\">\/\/ OK<\/span>\r\n<span class=\"hljs-built_in\">Object<\/span>.create(<span class=\"hljs-literal\">null<\/span>);      <span class=\"hljs-comment\">\/\/ OK<\/span>\r\n<span class=\"hljs-built_in\">Object<\/span>.create(<span class=\"hljs-literal\">undefined<\/span>); <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"hljs-built_in\">Object<\/span>.create(<span class=\"hljs-number\">1337<\/span>);      <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"hljs-built_in\">Object<\/span>.create(<span class=\"hljs-literal\">true<\/span>);      <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"hljs-built_in\">Object<\/span>.create(<span class=\"hljs-string\">\"oops\"<\/span>);    <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-26\">2.Object \u7c7b\u578b<\/h5>\n<p>Object \u7c7b\u578b\uff1a\u5b83\u662f\u6240\u6709 Object \u7c7b\u7684\u5b9e\u4f8b\u7684\u7c7b\u578b\uff0c\u5b83\u7531\u4ee5\u4e0b\u4e24\u4e2a\u63a5\u53e3\u6765\u5b9a\u4e49\uff1a<\/p>\n<ul>\n<li>Object \u63a5\u53e3\u5b9a\u4e49\u4e86 Object.prototype \u539f\u578b\u5bf9\u8c61\u4e0a\u7684\u5c5e\u6027\uff1b<\/li>\n<\/ul>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ node_modules\/typescript\/lib\/lib.es5.d.ts<\/span>\r\n<span class=\"hljs-keyword\">interface<\/span> Object {\r\n  <span class=\"hljs-attr\">constructor<\/span>: <span class=\"hljs-built_in\">Function<\/span>;\r\n  toString(): <span class=\"hljs-built_in\">string<\/span>;\r\n  toLocaleString(): <span class=\"hljs-built_in\">string<\/span>;\r\n  valueOf(): <span class=\"hljs-built_in\">Object<\/span>;\r\n  hasOwnProperty(v: PropertyKey): <span class=\"hljs-built_in\">boolean<\/span>;\r\n  isPrototypeOf(v: <span class=\"hljs-built_in\">Object<\/span>): <span class=\"hljs-built_in\">boolean<\/span>;\r\n  propertyIsEnumerable(v: PropertyKey): <span class=\"hljs-built_in\">boolean<\/span>;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<ul>\n<li>ObjectConstructor \u63a5\u53e3\u5b9a\u4e49\u4e86 Object \u7c7b\u7684\u5c5e\u6027\u3002<\/li>\n<\/ul>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ node_modules\/typescript\/lib\/lib.es5.d.ts<\/span>\r\n<span class=\"hljs-keyword\">interface<\/span> ObjectConstructor {\r\n  <span class=\"hljs-comment\">\/** Invocation via `new` *\/<\/span>\r\n  <span class=\"hljs-keyword\">new<\/span>(value?: <span class=\"hljs-built_in\">any<\/span>): <span class=\"hljs-built_in\">Object<\/span>;\r\n  <span class=\"hljs-comment\">\/** Invocation via function calls *\/<\/span>\r\n  (value?: <span class=\"hljs-built_in\">any<\/span>): <span class=\"hljs-built_in\">any<\/span>;\r\n  <span class=\"hljs-keyword\">readonly<\/span> prototype: <span class=\"hljs-built_in\">Object<\/span>;\r\n  getPrototypeOf(o: <span class=\"hljs-built_in\">any<\/span>): <span class=\"hljs-built_in\">any<\/span>;\r\n  <span class=\"hljs-comment\">\/\/ \u00b7\u00b7\u00b7<\/span>\r\n}\r\n\r\n<span class=\"hljs-keyword\">declare<\/span> <span class=\"hljs-keyword\">var<\/span> <span class=\"hljs-built_in\">Object<\/span>: ObjectConstructor;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>Object \u7c7b\u7684\u6240\u6709\u5b9e\u4f8b\u90fd\u7ee7\u627f\u4e86 Object \u63a5\u53e3\u4e2d\u7684\u6240\u6709\u5c5e\u6027\u3002<\/p>\n<h5 data-id=\"heading-27\">3.{} \u7c7b\u578b<\/h5>\n<p>{} \u7c7b\u578b\u63cf\u8ff0\u4e86\u4e00\u4e2a\u6ca1\u6709\u6210\u5458\u7684\u5bf9\u8c61\u3002\u5f53\u4f60\u8bd5\u56fe\u8bbf\u95ee\u8fd9\u6837\u4e00\u4e2a\u5bf9\u8c61\u7684\u4efb\u610f\u5c5e\u6027\u65f6\uff0cTypeScript \u4f1a\u4ea7\u751f\u4e00\u4e2a\u7f16\u8bd1\u65f6\u9519\u8bef\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ Type {}<\/span>\r\n<span class=\"hljs-keyword\">const<\/span> obj = {};\r\n\r\n<span class=\"hljs-comment\">\/\/ Error: Property 'prop' does not exist on type '{}'.<\/span>\r\nobj.prop = <span class=\"hljs-string\">\"semlinker\"<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4f46\u662f\uff0c\u4f60\u4ecd\u7136\u53ef\u4ee5\u4f7f\u7528\u5728 Object \u7c7b\u578b\u4e0a\u5b9a\u4e49\u7684\u6240\u6709\u5c5e\u6027\u548c\u65b9\u6cd5\uff0c\u8fd9\u4e9b\u5c5e\u6027\u548c\u65b9\u6cd5\u53ef\u901a\u8fc7 JavaScript \u7684\u539f\u578b\u94fe\u9690\u5f0f\u5730\u4f7f\u7528\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ Type {}<\/span>\r\n<span class=\"hljs-keyword\">const<\/span> obj = {};\r\n\r\n<span class=\"hljs-comment\">\/\/ \"[object Object]\"<\/span>\r\nobj.toString();\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-28\">2.13 Never \u7c7b\u578b<\/h4>\n<p><code>never<\/code>\u00a0\u7c7b\u578b\u8868\u793a\u7684\u662f\u90a3\u4e9b\u6c38\u4e0d\u5b58\u5728\u7684\u503c\u7684\u7c7b\u578b\u3002 \u4f8b\u5982\uff0c<code>never<\/code>\u00a0\u7c7b\u578b\u662f\u90a3\u4e9b\u603b\u662f\u4f1a\u629b\u51fa\u5f02\u5e38\u6216\u6839\u672c\u5c31\u4e0d\u4f1a\u6709\u8fd4\u56de\u503c\u7684\u51fd\u6570\u8868\u8fbe\u5f0f\u6216\u7bad\u5934\u51fd\u6570\u8868\u8fbe\u5f0f\u7684\u8fd4\u56de\u503c\u7c7b\u578b\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ \u8fd4\u56denever\u7684\u51fd\u6570\u5fc5\u987b\u5b58\u5728\u65e0\u6cd5\u8fbe\u5230\u7684\u7ec8\u70b9<\/span>\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">error<\/span>(<span class=\"hljs-params\">message: <span class=\"hljs-built_in\">string<\/span><\/span>): <span class=\"hljs-title\">never<\/span> <\/span>{\r\n  <span class=\"hljs-keyword\">throw<\/span> <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-built_in\">Error<\/span>(message);\r\n}\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">infiniteLoop<\/span>(): <span class=\"hljs-title\">never<\/span> <\/span>{\r\n  <span class=\"hljs-keyword\">while<\/span> (<span class=\"hljs-literal\">true<\/span>) {}\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728 TypeScript \u4e2d\uff0c\u53ef\u4ee5\u5229\u7528 never \u7c7b\u578b\u7684\u7279\u6027\u6765\u5b9e\u73b0\u5168\u9762\u6027\u68c0\u67e5\uff0c\u5177\u4f53\u793a\u4f8b\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> Foo = <span class=\"hljs-built_in\">string<\/span> | <span class=\"hljs-built_in\">number<\/span>;\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">controlFlowAnalysisWithNever<\/span>(<span class=\"hljs-params\">foo: Foo<\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> foo === <span class=\"hljs-string\">\"string\"<\/span>) {\r\n    <span class=\"hljs-comment\">\/\/ \u8fd9\u91cc foo \u88ab\u6536\u7a84\u4e3a string \u7c7b\u578b<\/span>\r\n  } <span class=\"hljs-keyword\">else<\/span> <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> foo === <span class=\"hljs-string\">\"number\"<\/span>) {\r\n    <span class=\"hljs-comment\">\/\/ \u8fd9\u91cc foo \u88ab\u6536\u7a84\u4e3a number \u7c7b\u578b<\/span>\r\n  } <span class=\"hljs-keyword\">else<\/span> {\r\n    <span class=\"hljs-comment\">\/\/ foo \u5728\u8fd9\u91cc\u662f never<\/span>\r\n    <span class=\"hljs-keyword\">const<\/span> check: <span class=\"hljs-built_in\">never<\/span> = foo;\r\n  }\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u6ce8\u610f\u5728 else \u5206\u652f\u91cc\u9762\uff0c\u6211\u4eec\u628a\u6536\u7a84\u4e3a never \u7684 foo \u8d4b\u503c\u7ed9\u4e00\u4e2a\u663e\u793a\u58f0\u660e\u7684 never \u53d8\u91cf\u3002\u5982\u679c\u4e00\u5207\u903b\u8f91\u6b63\u786e\uff0c\u90a3\u4e48\u8fd9\u91cc\u5e94\u8be5\u80fd\u591f\u7f16\u8bd1\u901a\u8fc7\u3002\u4f46\u662f\u5047\u5982\u540e\u6765\u6709\u4e00\u5929\u4f60\u7684\u540c\u4e8b\u4fee\u6539\u4e86 Foo \u7684\u7c7b\u578b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> Foo = <span class=\"hljs-built_in\">string<\/span> | <span class=\"hljs-built_in\">number<\/span> | <span class=\"hljs-built_in\">boolean<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u7136\u800c\u4ed6\u5fd8\u8bb0\u540c\u65f6\u4fee\u6539\u00a0<code>controlFlowAnalysisWithNever<\/code>\u00a0\u65b9\u6cd5\u4e2d\u7684\u63a7\u5236\u6d41\u7a0b\uff0c\u8fd9\u65f6\u5019 else \u5206\u652f\u7684 foo \u7c7b\u578b\u4f1a\u88ab\u6536\u7a84\u4e3a\u00a0<code>boolean<\/code>\u00a0\u7c7b\u578b\uff0c\u5bfc\u81f4\u65e0\u6cd5\u8d4b\u503c\u7ed9 never \u7c7b\u578b\uff0c\u8fd9\u65f6\u5c31\u4f1a\u4ea7\u751f\u4e00\u4e2a\u7f16\u8bd1\u9519\u8bef\u3002\u901a\u8fc7\u8fd9\u4e2a\u65b9\u5f0f\uff0c\u6211\u4eec\u53ef\u4ee5\u786e\u4fdd<\/p>\n<p><code>controlFlowAnalysisWithNever<\/code>\u00a0\u65b9\u6cd5\u603b\u662f\u7a77\u5c3d\u4e86 Foo \u7684\u6240\u6709\u53ef\u80fd\u7c7b\u578b\u3002 \u901a\u8fc7\u8fd9\u4e2a\u793a\u4f8b\uff0c\u6211\u4eec\u53ef\u4ee5\u5f97\u51fa\u4e00\u4e2a\u7ed3\u8bba\uff1a<strong>\u4f7f\u7528 never \u907f\u514d\u51fa\u73b0\u65b0\u589e\u4e86\u8054\u5408\u7c7b\u578b\u6ca1\u6709\u5bf9\u5e94\u7684\u5b9e\u73b0\uff0c\u76ee\u7684\u5c31\u662f\u5199\u51fa\u7c7b\u578b\u7edd\u5bf9\u5b89\u5168\u7684\u4ee3\u7801\u3002<\/strong><\/p>\n<h3 data-id=\"heading-29\">\u4e09\u3001TypeScript \u65ad\u8a00<\/h3>\n<h4 data-id=\"heading-30\">3.1 \u7c7b\u578b\u65ad\u8a00<\/h4>\n<p>\u6709\u65f6\u5019\u4f60\u4f1a\u9047\u5230\u8fd9\u6837\u7684\u60c5\u51b5\uff0c\u4f60\u4f1a\u6bd4 TypeScript \u66f4\u4e86\u89e3\u67d0\u4e2a\u503c\u7684\u8be6\u7ec6\u4fe1\u606f\u3002\u901a\u5e38\u8fd9\u4f1a\u53d1\u751f\u5728\u4f60\u6e05\u695a\u5730\u77e5\u9053\u4e00\u4e2a\u5b9e\u4f53\u5177\u6709\u6bd4\u5b83\u73b0\u6709\u7c7b\u578b\u66f4\u786e\u5207\u7684\u7c7b\u578b\u3002<\/p>\n<p>\u901a\u8fc7\u7c7b\u578b\u65ad\u8a00\u8fd9\u79cd\u65b9\u5f0f\u53ef\u4ee5\u544a\u8bc9\u7f16\u8bd1\u5668\uff0c\u201c\u76f8\u4fe1\u6211\uff0c\u6211\u77e5\u9053\u81ea\u5df1\u5728\u5e72\u4ec0\u4e48\u201d\u3002\u7c7b\u578b\u65ad\u8a00\u597d\u6bd4\u5176\u4ed6\u8bed\u8a00\u91cc\u7684\u7c7b\u578b\u8f6c\u6362\uff0c\u4f46\u662f\u4e0d\u8fdb\u884c\u7279\u6b8a\u7684\u6570\u636e\u68c0\u67e5\u548c\u89e3\u6784\u3002\u5b83\u6ca1\u6709\u8fd0\u884c\u65f6\u7684\u5f71\u54cd\uff0c\u53ea\u662f\u5728\u7f16\u8bd1\u9636\u6bb5\u8d77\u4f5c\u7528\u3002<\/p>\n<p>\u7c7b\u578b\u65ad\u8a00\u6709\u4e24\u79cd\u5f62\u5f0f\uff1a<\/p>\n<h5 data-id=\"heading-31\">1.\u201c\u5c16\u62ec\u53f7\u201d \u8bed\u6cd5<\/h5>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> someValue: <span class=\"hljs-built_in\">any<\/span> = <span class=\"hljs-string\">\"this is a string\"<\/span>;\r\n<span class=\"hljs-keyword\">let<\/span> strLength: <span class=\"hljs-built_in\">number<\/span> = (&lt;<span class=\"hljs-built_in\">string<\/span>&gt;someValue).length;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-32\">2.as \u8bed\u6cd5<\/h5>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> someValue: <span class=\"hljs-built_in\">any<\/span> = <span class=\"hljs-string\">\"this is a string\"<\/span>;\r\n<span class=\"hljs-keyword\">let<\/span> strLength: <span class=\"hljs-built_in\">number<\/span> = (someValue <span class=\"hljs-keyword\">as<\/span> <span class=\"hljs-built_in\">string<\/span>).length;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-33\">3.2 \u975e\u7a7a\u65ad\u8a00<\/h4>\n<p>\u5728\u4e0a\u4e0b\u6587\u4e2d\u5f53\u7c7b\u578b\u68c0\u67e5\u5668\u65e0\u6cd5\u65ad\u5b9a\u7c7b\u578b\u65f6\uff0c\u4e00\u4e2a\u65b0\u7684\u540e\u7f00\u8868\u8fbe\u5f0f\u64cd\u4f5c\u7b26\u00a0<code>!<\/code>\u00a0\u53ef\u4ee5\u7528\u4e8e\u65ad\u8a00\u64cd\u4f5c\u5bf9\u8c61\u662f\u975e null \u548c\u975e undefined \u7c7b\u578b\u3002<strong>\u5177\u4f53\u800c\u8a00\uff0cx! \u5c06\u4ece x \u503c\u57df\u4e2d\u6392\u9664 null \u548c undefined \u3002<\/strong><\/p>\n<p>\u90a3\u4e48\u975e\u7a7a\u65ad\u8a00\u64cd\u4f5c\u7b26\u5230\u5e95\u6709\u4ec0\u4e48\u7528\u5462\uff1f\u4e0b\u9762\u6211\u4eec\u5148\u6765\u770b\u4e00\u4e0b\u975e\u7a7a\u65ad\u8a00\u64cd\u4f5c\u7b26\u7684\u4e00\u4e9b\u4f7f\u7528\u573a\u666f\u3002<\/p>\n<h5 data-id=\"heading-34\">1.\u5ffd\u7565 undefined \u548c null \u7c7b\u578b<\/h5>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">myFunc<\/span>(<span class=\"hljs-params\">maybeString: <span class=\"hljs-built_in\">string<\/span> | <span class=\"hljs-literal\">undefined<\/span> | <span class=\"hljs-literal\">null<\/span><\/span>) <\/span>{\r\n  <span class=\"hljs-comment\">\/\/ Type 'string | null | undefined' is not assignable to type 'string'.<\/span>\r\n  <span class=\"hljs-comment\">\/\/ Type 'undefined' is not assignable to type 'string'. <\/span>\r\n  <span class=\"hljs-keyword\">const<\/span> onlyString: <span class=\"hljs-built_in\">string<\/span> = maybeString; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n  <span class=\"hljs-keyword\">const<\/span> ignoreUndefinedAndNull: <span class=\"hljs-built_in\">string<\/span> = maybeString!; <span class=\"hljs-comment\">\/\/ Ok<\/span>\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-35\">2.\u8c03\u7528\u51fd\u6570\u65f6\u5ffd\u7565 undefined \u7c7b\u578b<\/h5>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> NumGenerator = <span class=\"hljs-function\">() =&gt;<\/span> <span class=\"hljs-built_in\">number<\/span>;\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">myFunc<\/span>(<span class=\"hljs-params\">numGenerator: NumGenerator | <span class=\"hljs-literal\">undefined<\/span><\/span>) <\/span>{\r\n  <span class=\"hljs-comment\">\/\/ Object is possibly 'undefined'.(2532)<\/span>\r\n  <span class=\"hljs-comment\">\/\/ Cannot invoke an object which is possibly 'undefined'.(2722)<\/span>\r\n  <span class=\"hljs-keyword\">const<\/span> num1 = numGenerator(); <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n  <span class=\"hljs-keyword\">const<\/span> num2 = numGenerator!(); <span class=\"hljs-comment\">\/\/OK<\/span>\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u56e0\u4e3a\u00a0<code>!<\/code>\u00a0\u975e\u7a7a\u65ad\u8a00\u64cd\u4f5c\u7b26\u4f1a\u4ece\u7f16\u8bd1\u751f\u6210\u7684 JavaScript \u4ee3\u7801\u4e2d\u79fb\u9664\uff0c\u6240\u4ee5\u5728\u5b9e\u9645\u4f7f\u7528\u7684\u8fc7\u7a0b\u4e2d\uff0c\u8981\u7279\u522b\u6ce8\u610f\u3002\u6bd4\u5982\u4e0b\u9762\u8fd9\u4e2a\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">const<\/span> a: <span class=\"hljs-built_in\">number<\/span> | <span class=\"hljs-literal\">undefined<\/span> = <span class=\"hljs-literal\">undefined<\/span>;\r\n<span class=\"hljs-keyword\">const<\/span> b: <span class=\"hljs-built_in\">number<\/span> = a!;\r\n<span class=\"hljs-built_in\">console<\/span>.log(b); \r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a TS \u4ee3\u7801\u4f1a\u7f16\u8bd1\u751f\u6210\u4ee5\u4e0b ES5 \u4ee3\u7801\uff1a<\/p>\n<pre><code class=\"hljs language-javascript copyable\" lang=\"javascript\"><span class=\"hljs-meta\">\"use strict\"<\/span>;\r\n<span class=\"hljs-keyword\">const<\/span> a = <span class=\"hljs-literal\">undefined<\/span>;\r\n<span class=\"hljs-keyword\">const<\/span> b = a;\r\n<span class=\"hljs-built_in\">console<\/span>.log(b);\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u867d\u7136\u5728 TS \u4ee3\u7801\u4e2d\uff0c\u6211\u4eec\u4f7f\u7528\u4e86\u975e\u7a7a\u65ad\u8a00\uff0c\u4f7f\u5f97\u00a0<code>const b: number = a!;<\/code>\u00a0\u8bed\u53e5\u53ef\u4ee5\u901a\u8fc7 TypeScript \u7c7b\u578b\u68c0\u67e5\u5668\u7684\u68c0\u67e5\u3002\u4f46\u5728\u751f\u6210\u7684 ES5 \u4ee3\u7801\u4e2d\uff0c<code>!<\/code>\u00a0\u975e\u7a7a\u65ad\u8a00\u64cd\u4f5c\u7b26\u88ab\u79fb\u9664\u4e86\uff0c\u6240\u4ee5\u5728\u6d4f\u89c8\u5668\u4e2d\u6267\u884c\u4ee5\u4e0a\u4ee3\u7801\uff0c\u5728\u63a7\u5236\u53f0\u4f1a\u8f93\u51fa\u00a0<code>undefined<\/code>\u3002<\/p>\n<h4 data-id=\"heading-36\">3.3 \u786e\u5b9a\u8d4b\u503c\u65ad\u8a00<\/h4>\n<p>\u5728 TypeScript 2.7 \u7248\u672c\u4e2d\u5f15\u5165\u4e86\u786e\u5b9a\u8d4b\u503c\u65ad\u8a00\uff0c\u5373\u5141\u8bb8\u5728\u5b9e\u4f8b\u5c5e\u6027\u548c\u53d8\u91cf\u58f0\u660e\u540e\u9762\u653e\u7f6e\u4e00\u4e2a\u00a0<code>!<\/code>\u00a0\u53f7\uff0c\u4ece\u800c\u544a\u8bc9 TypeScript \u8be5\u5c5e\u6027\u4f1a\u88ab\u660e\u786e\u5730\u8d4b\u503c\u3002\u4e3a\u4e86\u66f4\u597d\u5730\u7406\u89e3\u5b83\u7684\u4f5c\u7528\uff0c\u6211\u4eec\u6765\u770b\u4e2a\u5177\u4f53\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> x: <span class=\"hljs-built_in\">number<\/span>;\r\ninitialize();\r\n<span class=\"hljs-comment\">\/\/ Variable 'x' is used before being assigned.(2454)<\/span>\r\n<span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-number\">2<\/span> * x); <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">initialize<\/span>() <\/span>{\r\n  x = <span class=\"hljs-number\">10<\/span>;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5f88\u660e\u663e\u8be5\u5f02\u5e38\u4fe1\u606f\u662f\u8bf4\u53d8\u91cf x \u5728\u8d4b\u503c\u524d\u88ab\u4f7f\u7528\u4e86\uff0c\u8981\u89e3\u51b3\u8be5\u95ee\u9898\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u786e\u5b9a\u8d4b\u503c\u65ad\u8a00\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> x!: <span class=\"hljs-built_in\">number<\/span>;\r\ninitialize();\r\n<span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-number\">2<\/span> * x); <span class=\"hljs-comment\">\/\/ Ok<\/span>\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">initialize<\/span>() <\/span>{\r\n  x = <span class=\"hljs-number\">10<\/span>;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u901a\u8fc7\u00a0<code>let x!: number;<\/code>\u00a0\u786e\u5b9a\u8d4b\u503c\u65ad\u8a00\uff0cTypeScript \u7f16\u8bd1\u5668\u5c31\u4f1a\u77e5\u9053\u8be5\u5c5e\u6027\u4f1a\u88ab\u660e\u786e\u5730\u8d4b\u503c\u3002<\/p>\n<h3 data-id=\"heading-37\">\u56db\u3001\u7c7b\u578b\u5b88\u536b<\/h3>\n<p><strong>\u7c7b\u578b\u4fdd\u62a4\u662f\u53ef\u6267\u884c\u8fd0\u884c\u65f6\u68c0\u67e5\u7684\u4e00\u79cd\u8868\u8fbe\u5f0f\uff0c\u7528\u4e8e\u786e\u4fdd\u8be5\u7c7b\u578b\u5728\u4e00\u5b9a\u7684\u8303\u56f4\u5185\u3002<\/strong>\u00a0\u6362\u53e5\u8bdd\u8bf4\uff0c\u7c7b\u578b\u4fdd\u62a4\u53ef\u4ee5\u4fdd\u8bc1\u4e00\u4e2a\u5b57\u7b26\u4e32\u662f\u4e00\u4e2a\u5b57\u7b26\u4e32\uff0c\u5c3d\u7ba1\u5b83\u7684\u503c\u4e5f\u53ef\u4ee5\u662f\u4e00\u4e2a\u6570\u503c\u3002\u7c7b\u578b\u4fdd\u62a4\u4e0e\u7279\u6027\u68c0\u6d4b\u5e76\u4e0d\u662f\u5b8c\u5168\u4e0d\u540c\uff0c\u5176\u4e3b\u8981\u601d\u60f3\u662f\u5c1d\u8bd5\u68c0\u6d4b\u5c5e\u6027\u3001\u65b9\u6cd5\u6216\u539f\u578b\uff0c\u4ee5\u786e\u5b9a\u5982\u4f55\u5904\u7406\u503c\u3002\u76ee\u524d\u4e3b\u8981\u6709\u56db\u79cd\u7684\u65b9\u5f0f\u6765\u5b9e\u73b0\u7c7b\u578b\u4fdd\u62a4\uff1a<\/p>\n<h4 data-id=\"heading-38\">4.1 in \u5173\u952e\u5b57<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Admin {\r\n  <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-built_in\">string<\/span>;\r\n  privileges: <span class=\"hljs-built_in\">string<\/span>[];\r\n}\r\n\r\n<span class=\"hljs-keyword\">interface<\/span> Employee {\r\n  <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-built_in\">string<\/span>;\r\n  startDate: <span class=\"hljs-built_in\">Date<\/span>;\r\n}\r\n\r\n<span class=\"hljs-keyword\">type<\/span> UnknownEmployee = Employee | Admin;\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">printEmployeeInformation<\/span>(<span class=\"hljs-params\">emp: UnknownEmployee<\/span>) <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"Name: \"<\/span> + emp.name);\r\n  <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-string\">\"privileges\"<\/span> <span class=\"hljs-keyword\">in<\/span> emp) {\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"Privileges: \"<\/span> + emp.privileges);\r\n  }\r\n  <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-string\">\"startDate\"<\/span> <span class=\"hljs-keyword\">in<\/span> emp) {\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"Start Date: \"<\/span> + emp.startDate);\r\n  }\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-39\">4.2 typeof \u5173\u952e\u5b57<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">padLeft<\/span>(<span class=\"hljs-params\">value: <span class=\"hljs-built_in\">string<\/span>, padding: <span class=\"hljs-built_in\">string<\/span> | <span class=\"hljs-built_in\">number<\/span><\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> padding === <span class=\"hljs-string\">\"number\"<\/span>) {\r\n      <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-built_in\">Array<\/span>(padding + <span class=\"hljs-number\">1<\/span>).join(<span class=\"hljs-string\">\" \"<\/span>) + value;\r\n  }\r\n  <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> padding === <span class=\"hljs-string\">\"string\"<\/span>) {\r\n      <span class=\"hljs-keyword\">return<\/span> padding + value;\r\n  }\r\n  <span class=\"hljs-keyword\">throw<\/span> <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-built_in\">Error<\/span>(<span class=\"hljs-string\">`Expected string or number, got '<span class=\"hljs-subst\">${padding}<\/span>'.`<\/span>);\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><code>typeof<\/code>\u00a0\u7c7b\u578b\u4fdd\u62a4\u53ea\u652f\u6301\u4e24\u79cd\u5f62\u5f0f\uff1a<code>typeof v === \"typename\"<\/code>\u00a0\u548c\u00a0<code>typeof v !== typename<\/code>\uff0c<code>\"typename\"<\/code>\u00a0\u5fc5\u987b\u662f\u00a0<code>\"number\"<\/code>\uff0c\u00a0<code>\"string\"<\/code>\uff0c\u00a0<code>\"boolean\"<\/code>\u00a0\u6216\u00a0<code>\"symbol\"<\/code>\u3002 \u4f46\u662f TypeScript \u5e76\u4e0d\u4f1a\u963b\u6b62\u4f60\u4e0e\u5176\u5b83\u5b57\u7b26\u4e32\u6bd4\u8f83\uff0c\u8bed\u8a00\u4e0d\u4f1a\u628a\u90a3\u4e9b\u8868\u8fbe\u5f0f\u8bc6\u522b\u4e3a\u7c7b\u578b\u4fdd\u62a4\u3002<\/p>\n<h4 data-id=\"heading-40\">4.3 instanceof \u5173\u952e\u5b57<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Padder {\r\n  getPaddingString(): <span class=\"hljs-built_in\">string<\/span>;\r\n}\r\n\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">SpaceRepeatingPadder<\/span> <span class=\"hljs-title\">implements<\/span> <span class=\"hljs-title\">Padder<\/span> <\/span>{\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\"><span class=\"hljs-keyword\">private<\/span> numSpaces: <span class=\"hljs-built_in\">number<\/span><\/span>)<\/span> {}\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">getPaddingString<\/span>()<\/span> {\r\n    <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-built_in\">Array<\/span>(<span class=\"hljs-built_in\">this<\/span>.numSpaces + <span class=\"hljs-number\">1<\/span>).join(<span class=\"hljs-string\">\" \"<\/span>);\r\n  }\r\n}\r\n\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">StringPadder<\/span> <span class=\"hljs-title\">implements<\/span> <span class=\"hljs-title\">Padder<\/span> <\/span>{\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\"><span class=\"hljs-keyword\">private<\/span> value: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> {}\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">getPaddingString<\/span>()<\/span> {\r\n    <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-built_in\">this<\/span>.value;\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> padder: Padder = <span class=\"hljs-keyword\">new<\/span> SpaceRepeatingPadder(<span class=\"hljs-number\">6<\/span>);\r\n\r\n<span class=\"hljs-keyword\">if<\/span> (padder <span class=\"hljs-keyword\">instanceof<\/span> SpaceRepeatingPadder) {\r\n  <span class=\"hljs-comment\">\/\/ padder\u7684\u7c7b\u578b\u6536\u7a84\u4e3a 'SpaceRepeatingPadder'<\/span>\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-41\">4.4 \u81ea\u5b9a\u4e49\u7c7b\u578b\u4fdd\u62a4\u7684\u7c7b\u578b\u8c13\u8bcd<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">isNumber<\/span>(<span class=\"hljs-params\">x: <span class=\"hljs-built_in\">any<\/span><\/span>): <span class=\"hljs-title\">x<\/span> <span class=\"hljs-title\">is<\/span> <span class=\"hljs-title\">number<\/span> <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-keyword\">typeof<\/span> x === <span class=\"hljs-string\">\"number\"<\/span>;\r\n}\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">isString<\/span>(<span class=\"hljs-params\">x: <span class=\"hljs-built_in\">any<\/span><\/span>): <span class=\"hljs-title\">x<\/span> <span class=\"hljs-title\">is<\/span> <span class=\"hljs-title\">string<\/span> <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-keyword\">typeof<\/span> x === <span class=\"hljs-string\">\"string\"<\/span>;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h3 data-id=\"heading-42\">\u4e94\u3001\u8054\u5408\u7c7b\u578b\u548c\u7c7b\u578b\u522b\u540d<\/h3>\n<h4 data-id=\"heading-43\">5.1 \u8054\u5408\u7c7b\u578b<\/h4>\n<p>\u8054\u5408\u7c7b\u578b\u901a\u5e38\u4e0e\u00a0<code>null<\/code>\u00a0\u6216\u00a0<code>undefined<\/code>\u00a0\u4e00\u8d77\u4f7f\u7528\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">const<\/span> sayHello = <span class=\"hljs-function\">(<span class=\"hljs-params\">name: <span class=\"hljs-built_in\">string<\/span> | <span class=\"hljs-literal\">undefined<\/span><\/span>) =&gt;<\/span> {\r\n  <span class=\"hljs-comment\">\/* ... *\/<\/span>\r\n};\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u8fd9\u91cc\u00a0<code>name<\/code>\u00a0\u7684\u7c7b\u578b\u662f\u00a0<code>string | undefined<\/code>\u00a0\u610f\u5473\u7740\u53ef\u4ee5\u5c06\u00a0<code>string<\/code>\u00a0\u6216\u00a0<code>undefined<\/code>\u00a0\u7684\u503c\u4f20\u9012\u7ed9<code>sayHello<\/code>\u00a0\u51fd\u6570\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\">sayHello(<span class=\"hljs-string\">\"semlinker\"<\/span>);\r\nsayHello(<span class=\"hljs-literal\">undefined<\/span>);\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u901a\u8fc7\u8fd9\u4e2a\u793a\u4f8b\uff0c\u4f60\u53ef\u4ee5\u51ed\u76f4\u89c9\u77e5\u9053\u7c7b\u578b A \u548c\u7c7b\u578b B \u8054\u5408\u540e\u7684\u7c7b\u578b\u662f\u540c\u65f6\u63a5\u53d7 A \u548c B \u503c\u7684\u7c7b\u578b\u3002\u6b64\u5916\uff0c\u5bf9\u4e8e\u8054\u5408\u7c7b\u578b\u6765\u8bf4\uff0c\u4f60\u53ef\u80fd\u4f1a\u9047\u5230\u4ee5\u4e0b\u7684\u7528\u6cd5\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> num: <span class=\"hljs-number\">1<\/span> | <span class=\"hljs-number\">2<\/span> = <span class=\"hljs-number\">1<\/span>;\r\n<span class=\"hljs-keyword\">type<\/span> EventNames = <span class=\"hljs-string\">'click'<\/span> | <span class=\"hljs-string\">'scroll'<\/span> | <span class=\"hljs-string\">'mousemove'<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a\u793a\u4f8b\u4e2d\u7684\u00a0<code>1<\/code>\u3001<code>2<\/code>\u00a0\u6216\u00a0<code>'click'<\/code>\u00a0\u88ab\u79f0\u4e3a\u5b57\u9762\u91cf\u7c7b\u578b\uff0c\u7528\u6765\u7ea6\u675f\u53d6\u503c\u53ea\u80fd\u662f\u67d0\u51e0\u4e2a\u503c\u4e2d\u7684\u4e00\u4e2a\u3002<\/p>\n<h4 data-id=\"heading-44\">5.2 \u53ef\u8fa8\u8bc6\u8054\u5408<\/h4>\n<p>TypeScript \u53ef\u8fa8\u8bc6\u8054\u5408\uff08Discriminated Unions\uff09\u7c7b\u578b\uff0c\u4e5f\u79f0\u4e3a\u4ee3\u6570\u6570\u636e\u7c7b\u578b\u6216\u6807\u7b7e\u8054\u5408\u7c7b\u578b\u3002<strong>\u5b83\u5305\u542b 3 \u4e2a\u8981\u70b9\uff1a\u53ef\u8fa8\u8bc6\u3001\u8054\u5408\u7c7b\u578b\u548c\u7c7b\u578b\u5b88\u536b\u3002<\/strong><\/p>\n<p>\u8fd9\u79cd\u7c7b\u578b\u7684\u672c\u8d28\u662f\u7ed3\u5408\u8054\u5408\u7c7b\u578b\u548c\u5b57\u9762\u91cf\u7c7b\u578b\u7684\u4e00\u79cd\u7c7b\u578b\u4fdd\u62a4\u65b9\u6cd5\u3002<strong>\u5982\u679c\u4e00\u4e2a\u7c7b\u578b\u662f\u591a\u4e2a\u7c7b\u578b\u7684\u8054\u5408\u7c7b\u578b\uff0c\u4e14\u591a\u4e2a\u7c7b\u578b\u542b\u6709\u4e00\u4e2a\u516c\u5171\u5c5e\u6027\uff0c\u90a3\u4e48\u5c31\u53ef\u4ee5\u5229\u7528\u8fd9\u4e2a\u516c\u5171\u5c5e\u6027\uff0c\u6765\u521b\u5efa\u4e0d\u540c\u7684\u7c7b\u578b\u4fdd\u62a4\u533a\u5757\u3002<\/strong><\/p>\n<h5 data-id=\"heading-45\">1.\u53ef\u8fa8\u8bc6<\/h5>\n<p>\u53ef\u8fa8\u8bc6\u8981\u6c42\u8054\u5408\u7c7b\u578b\u4e2d\u7684\u6bcf\u4e2a\u5143\u7d20\u90fd\u542b\u6709\u4e00\u4e2a\u5355\u4f8b\u7c7b\u578b\u5c5e\u6027\uff0c\u6bd4\u5982\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-built_in\">enum<\/span> CarTransmission {\r\n  Automatic = <span class=\"hljs-number\">200<\/span>,\r\n  Manual = <span class=\"hljs-number\">300<\/span>\r\n}\r\n\r\n<span class=\"hljs-keyword\">interface<\/span> Motorcycle {\r\n  <span class=\"hljs-attr\">vType<\/span>: <span class=\"hljs-string\">\"motorcycle\"<\/span>; <span class=\"hljs-comment\">\/\/ discriminant<\/span>\r\n  make: <span class=\"hljs-built_in\">number<\/span>; <span class=\"hljs-comment\">\/\/ year<\/span>\r\n}\r\n\r\n<span class=\"hljs-keyword\">interface<\/span> Car {\r\n  <span class=\"hljs-attr\">vType<\/span>: <span class=\"hljs-string\">\"car\"<\/span>; <span class=\"hljs-comment\">\/\/ discriminant<\/span>\r\n  transmission: CarTransmission\r\n}\r\n\r\n<span class=\"hljs-keyword\">interface<\/span> Truck {\r\n  <span class=\"hljs-attr\">vType<\/span>: <span class=\"hljs-string\">\"truck\"<\/span>; <span class=\"hljs-comment\">\/\/ discriminant<\/span>\r\n  capacity: <span class=\"hljs-built_in\">number<\/span>; <span class=\"hljs-comment\">\/\/ in tons<\/span>\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u4e0a\u8ff0\u4ee3\u7801\u4e2d\uff0c\u6211\u4eec\u5206\u522b\u5b9a\u4e49\u4e86\u00a0<code>Motorcycle<\/code>\u3001\u00a0<code>Car<\/code>\u00a0\u548c\u00a0<code>Truck<\/code>\u00a0\u4e09\u4e2a\u63a5\u53e3\uff0c\u5728\u8fd9\u4e9b\u63a5\u53e3\u4e2d\u90fd\u5305\u542b\u4e00\u4e2a\u00a0<code>vType<\/code>\u00a0\u5c5e\u6027\uff0c\u8be5\u5c5e\u6027\u88ab\u79f0\u4e3a\u53ef\u8fa8\u8bc6\u7684\u5c5e\u6027\uff0c\u800c\u5176\u5b83\u7684\u5c5e\u6027\u53ea\u8ddf\u7279\u6027\u7684\u63a5\u53e3\u76f8\u5173\u3002<\/p>\n<h5 data-id=\"heading-46\">2.\u8054\u5408\u7c7b\u578b<\/h5>\n<p>\u57fa\u4e8e\u524d\u9762\u5b9a\u4e49\u4e86\u4e09\u4e2a\u63a5\u53e3\uff0c\u6211\u4eec\u53ef\u4ee5\u521b\u5efa\u4e00\u4e2a\u00a0<code>Vehicle<\/code>\u00a0\u8054\u5408\u7c7b\u578b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> Vehicle = Motorcycle | Car | Truck;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u73b0\u5728\u6211\u4eec\u5c31\u53ef\u4ee5\u5f00\u59cb\u4f7f\u7528\u00a0<code>Vehicle<\/code>\u00a0\u8054\u5408\u7c7b\u578b\uff0c\u5bf9\u4e8e\u00a0<code>Vehicle<\/code>\u00a0\u7c7b\u578b\u7684\u53d8\u91cf\uff0c\u5b83\u53ef\u4ee5\u8868\u793a\u4e0d\u540c\u7c7b\u578b\u7684\u8f66\u8f86\u3002<\/p>\n<h5 data-id=\"heading-47\">3.\u7c7b\u578b\u5b88\u536b<\/h5>\n<p>\u4e0b\u9762\u6211\u4eec\u6765\u5b9a\u4e49\u4e00\u4e2a\u00a0<code>evaluatePrice<\/code>\u00a0\u65b9\u6cd5\uff0c\u8be5\u65b9\u6cd5\u7528\u4e8e\u6839\u636e\u8f66\u8f86\u7684\u7c7b\u578b\u3001\u5bb9\u91cf\u548c\u8bc4\u4f30\u56e0\u5b50\u6765\u8ba1\u7b97\u4ef7\u683c\uff0c\u5177\u4f53\u5b9e\u73b0\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">const<\/span> EVALUATION_FACTOR = <span class=\"hljs-built_in\">Math<\/span>.PI; \r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">evaluatePrice<\/span>(<span class=\"hljs-params\">vehicle: Vehicle<\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> vehicle.capacity * EVALUATION_FACTOR;\r\n}\r\n\r\n<span class=\"hljs-keyword\">const<\/span> myTruck: Truck = { <span class=\"hljs-attr\">vType<\/span>: <span class=\"hljs-string\">\"truck\"<\/span>, <span class=\"hljs-attr\">capacity<\/span>: <span class=\"hljs-number\">9.5<\/span> };\r\nevaluatePrice(myTruck);\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5bf9\u4e8e\u4ee5\u4e0a\u4ee3\u7801\uff0cTypeScript \u7f16\u8bd1\u5668\u5c06\u4f1a\u63d0\u793a\u4ee5\u4e0b\u9519\u8bef\u4fe1\u606f\uff1a<\/p>\n<pre><code class=\"copyable\">Property 'capacity' does not exist on type 'Vehicle'.\r\nProperty 'capacity' does not exist on type 'Motorcycle'.\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u539f\u56e0\u662f\u5728 Motorcycle \u63a5\u53e3\u4e2d\uff0c\u5e76\u4e0d\u5b58\u5728\u00a0<code>capacity<\/code>\u00a0\u5c5e\u6027\uff0c\u800c\u5bf9\u4e8e Car \u63a5\u53e3\u6765\u8bf4\uff0c\u5b83\u4e5f\u4e0d\u5b58\u5728\u00a0<code>capacity<\/code>\u00a0\u5c5e\u6027\u3002\u90a3\u4e48\uff0c\u73b0\u5728\u6211\u4eec\u5e94\u8be5\u5982\u4f55\u89e3\u51b3\u4ee5\u4e0a\u95ee\u9898\u5462\uff1f\u8fd9\u65f6\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u7c7b\u578b\u5b88\u536b\u3002\u4e0b\u9762\u6211\u4eec\u6765\u91cd\u6784\u4e00\u4e0b\u524d\u9762\u5b9a\u4e49\u7684\u00a0<code>evaluatePrice<\/code>\u00a0\u65b9\u6cd5\uff0c\u91cd\u6784\u540e\u7684\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">evaluatePrice<\/span>(<span class=\"hljs-params\">vehicle: Vehicle<\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">switch<\/span>(vehicle.vType) {\r\n    <span class=\"hljs-keyword\">case<\/span> <span class=\"hljs-string\">\"car\"<\/span>:\r\n      <span class=\"hljs-keyword\">return<\/span> vehicle.transmission * EVALUATION_FACTOR;\r\n    <span class=\"hljs-keyword\">case<\/span> <span class=\"hljs-string\">\"truck\"<\/span>:\r\n      <span class=\"hljs-keyword\">return<\/span> vehicle.capacity * EVALUATION_FACTOR;\r\n    <span class=\"hljs-keyword\">case<\/span> <span class=\"hljs-string\">\"motorcycle\"<\/span>:\r\n      <span class=\"hljs-keyword\">return<\/span> vehicle.make * EVALUATION_FACTOR;\r\n  }\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u4ee5\u4e0a\u4ee3\u7801\u4e2d\uff0c\u6211\u4eec\u4f7f\u7528\u00a0<code>switch<\/code>\u00a0\u548c\u00a0<code>case<\/code>\u00a0\u8fd0\u7b97\u7b26\u6765\u5b9e\u73b0\u7c7b\u578b\u5b88\u536b\uff0c\u4ece\u800c\u786e\u4fdd\u5728\u00a0<code>evaluatePrice<\/code>\u00a0\u65b9\u6cd5\u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u5b89\u5168\u5730\u8bbf\u95ee\u00a0<code>vehicle<\/code>\u00a0\u5bf9\u8c61\u4e2d\u7684\u6240\u5305\u542b\u7684\u5c5e\u6027\uff0c\u6765\u6b63\u786e\u7684\u8ba1\u7b97\u8be5\u8f66\u8f86\u7c7b\u578b\u6240\u5bf9\u5e94\u7684\u4ef7\u683c\u3002<\/p>\n<h4 data-id=\"heading-48\">5.3 \u7c7b\u578b\u522b\u540d<\/h4>\n<p>\u7c7b\u578b\u522b\u540d\u7528\u6765\u7ed9\u4e00\u4e2a\u7c7b\u578b\u8d77\u4e2a\u65b0\u540d\u5b57\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> Message = <span class=\"hljs-built_in\">string<\/span> | <span class=\"hljs-built_in\">string<\/span>[];\r\n\r\n<span class=\"hljs-keyword\">let<\/span> greet = <span class=\"hljs-function\">(<span class=\"hljs-params\">message: Message<\/span>) =&gt;<\/span> {\r\n  <span class=\"hljs-comment\">\/\/ ...<\/span>\r\n};\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h3 data-id=\"heading-49\">\u516d\u3001\u4ea4\u53c9\u7c7b\u578b<\/h3>\n<p>\u5728 TypeScript \u4e2d\u4ea4\u53c9\u7c7b\u578b\u662f\u5c06\u591a\u4e2a\u7c7b\u578b\u5408\u5e76\u4e3a\u4e00\u4e2a\u7c7b\u578b\u3002\u901a\u8fc7\u00a0<code>&amp;<\/code>\u00a0\u8fd0\u7b97\u7b26\u53ef\u4ee5\u5c06\u73b0\u6709\u7684\u591a\u79cd\u7c7b\u578b\u53e0\u52a0\u5230\u4e00\u8d77\u6210\u4e3a\u4e00\u79cd\u7c7b\u578b\uff0c\u5b83\u5305\u542b\u4e86\u6240\u9700\u7684\u6240\u6709\u7c7b\u578b\u7684\u7279\u6027\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> PartialPointX = { <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-built_in\">number<\/span>; };\r\n<span class=\"hljs-keyword\">type<\/span> Point = PartialPointX &amp; { <span class=\"hljs-attr\">y<\/span>: <span class=\"hljs-built_in\">number<\/span>; };\r\n\r\n<span class=\"hljs-keyword\">let<\/span> point: Point = {\r\n  <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-number\">1<\/span>,\r\n  <span class=\"hljs-attr\">y<\/span>: <span class=\"hljs-number\">1<\/span>\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u4e0a\u9762\u4ee3\u7801\u4e2d\u6211\u4eec\u5148\u5b9a\u4e49\u4e86\u00a0<code>PartialPointX<\/code>\u00a0\u7c7b\u578b\uff0c\u63a5\u7740\u4f7f\u7528\u00a0<code>&amp;<\/code>\u00a0\u8fd0\u7b97\u7b26\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u00a0<code>Point<\/code>\u00a0\u7c7b\u578b\uff0c\u8868\u793a\u4e00\u4e2a\u542b\u6709 x \u548c y \u5750\u6807\u7684\u70b9\uff0c\u7136\u540e\u5b9a\u4e49\u4e86\u4e00\u4e2a\u00a0<code>Point<\/code>\u00a0\u7c7b\u578b\u7684\u53d8\u91cf\u5e76\u521d\u59cb\u5316\u3002<\/p>\n<h4 data-id=\"heading-50\">6.1 \u540c\u540d\u57fa\u7840\u7c7b\u578b\u5c5e\u6027\u7684\u5408\u5e76<\/h4>\n<p>\u90a3\u4e48\u73b0\u5728\u95ee\u9898\u6765\u4e86\uff0c\u5047\u8bbe\u5728\u5408\u5e76\u591a\u4e2a\u7c7b\u578b\u7684\u8fc7\u7a0b\u4e2d\uff0c\u521a\u597d\u51fa\u73b0\u67d0\u4e9b\u7c7b\u578b\u5b58\u5728\u76f8\u540c\u7684\u6210\u5458\uff0c\u4f46\u5bf9\u5e94\u7684\u7c7b\u578b\u53c8\u4e0d\u4e00\u81f4\uff0c\u6bd4\u5982\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> X {\r\n  <span class=\"hljs-attr\">c<\/span>: <span class=\"hljs-built_in\">string<\/span>;\r\n  d: <span class=\"hljs-built_in\">string<\/span>;\r\n}\r\n\r\n<span class=\"hljs-keyword\">interface<\/span> Y {\r\n  <span class=\"hljs-attr\">c<\/span>: <span class=\"hljs-built_in\">number<\/span>;\r\n  e: <span class=\"hljs-built_in\">string<\/span>\r\n}\r\n\r\n<span class=\"hljs-keyword\">type<\/span> XY = X &amp; Y;\r\n<span class=\"hljs-keyword\">type<\/span> YX = Y &amp; X;\r\n\r\n<span class=\"hljs-keyword\">let<\/span> p: XY;\r\n<span class=\"hljs-keyword\">let<\/span> q: YX;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u4e0a\u9762\u7684\u4ee3\u7801\u4e2d\uff0c\u63a5\u53e3 X \u548c\u63a5\u53e3 Y \u90fd\u542b\u6709\u4e00\u4e2a\u76f8\u540c\u7684\u6210\u5458 c\uff0c\u4f46\u5b83\u4eec\u7684\u7c7b\u578b\u4e0d\u4e00\u81f4\u3002\u5bf9\u4e8e\u8fd9\u79cd\u60c5\u51b5\uff0c\u6b64\u65f6 XY \u7c7b\u578b\u6216 YX \u7c7b\u578b\u4e2d\u6210\u5458 c \u7684\u7c7b\u578b\u662f\u4e0d\u662f\u53ef\u4ee5\u662f\u00a0<code>string<\/code>\u00a0\u6216\u00a0<code>number<\/code>\u00a0\u7c7b\u578b\u5462\uff1f\u6bd4\u5982\u4e0b\u9762\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\">p = { <span class=\"hljs-attr\">c<\/span>: <span class=\"hljs-number\">6<\/span>, <span class=\"hljs-attr\">d<\/span>: <span class=\"hljs-string\">\"d\"<\/span>, <span class=\"hljs-attr\">e<\/span>: <span class=\"hljs-string\">\"e\"<\/span> }; \r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p1-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/1bcfd462827046f1a4a5574de30780b2~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\">q = { <span class=\"hljs-attr\">c<\/span>: <span class=\"hljs-string\">\"c\"<\/span>, <span class=\"hljs-attr\">d<\/span>: <span class=\"hljs-string\">\"d\"<\/span>, <span class=\"hljs-attr\">e<\/span>: <span class=\"hljs-string\">\"e\"<\/span> }; \r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p9-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/1d4f87c84ea647308cac5393fdfa958a~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\u4e3a\u4ec0\u4e48\u63a5\u53e3 X \u548c\u63a5\u53e3 Y \u6df7\u5165\u540e\uff0c\u6210\u5458 c \u7684\u7c7b\u578b\u4f1a\u53d8\u6210\u00a0<code>never<\/code>\u00a0\u5462\uff1f\u8fd9\u662f\u56e0\u4e3a\u6df7\u5165\u540e\u6210\u5458 c \u7684\u7c7b\u578b\u4e3a\u00a0<code>string &amp; number<\/code>\uff0c\u5373\u6210\u5458 c \u7684\u7c7b\u578b\u65e2\u53ef\u4ee5\u662f\u00a0<code>string<\/code>\u00a0\u7c7b\u578b\u53c8\u53ef\u4ee5\u662f\u00a0<code>number<\/code>\u00a0\u7c7b\u578b\u3002\u5f88\u660e\u663e\u8fd9\u79cd\u7c7b\u578b\u662f\u4e0d\u5b58\u5728\u7684\uff0c\u6240\u4ee5\u6df7\u5165\u540e\u6210\u5458 c \u7684\u7c7b\u578b\u4e3a\u00a0<code>never<\/code>\u3002<\/p>\n<h4 data-id=\"heading-51\">6.2 \u540c\u540d\u975e\u57fa\u7840\u7c7b\u578b\u5c5e\u6027\u7684\u5408\u5e76<\/h4>\n<p>\u5728\u4e0a\u9762\u793a\u4f8b\u4e2d\uff0c\u521a\u597d\u63a5\u53e3 X \u548c\u63a5\u53e3 Y \u4e2d\u5185\u90e8\u6210\u5458 c \u7684\u7c7b\u578b\u90fd\u662f\u57fa\u672c\u6570\u636e\u7c7b\u578b\uff0c\u90a3\u4e48\u5982\u679c\u662f\u975e\u57fa\u672c\u6570\u636e\u7c7b\u578b\u7684\u8bdd\uff0c\u53c8\u4f1a\u662f\u4ec0\u4e48\u60c5\u5f62\u3002\u6211\u4eec\u6765\u770b\u4e2a\u5177\u4f53\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> D { d: <span class=\"hljs-built_in\">boolean<\/span>; }\r\n<span class=\"hljs-keyword\">interface<\/span> E { e: <span class=\"hljs-built_in\">string<\/span>; }\r\n<span class=\"hljs-keyword\">interface<\/span> F { f: <span class=\"hljs-built_in\">number<\/span>; }\r\n\r\n<span class=\"hljs-keyword\">interface<\/span> A { x: D; }\r\n<span class=\"hljs-keyword\">interface<\/span> B { x: E; }\r\n<span class=\"hljs-keyword\">interface<\/span> C { x: F; }\r\n\r\n<span class=\"hljs-keyword\">type<\/span> ABC = A &amp; B &amp; C;\r\n\r\n<span class=\"hljs-keyword\">let<\/span> abc: ABC = {\r\n  <span class=\"hljs-attr\">x<\/span>: {\r\n    <span class=\"hljs-attr\">d<\/span>: <span class=\"hljs-literal\">true<\/span>,\r\n    <span class=\"hljs-attr\">e<\/span>: <span class=\"hljs-string\">'semlinker'<\/span>,\r\n    <span class=\"hljs-attr\">f<\/span>: <span class=\"hljs-number\">666<\/span>\r\n  }\r\n};\r\n\r\n<span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'abc:'<\/span>, abc);\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a\u4ee3\u7801\u6210\u529f\u8fd0\u884c\u540e\uff0c\u63a7\u5236\u53f0\u4f1a\u8f93\u51fa\u4ee5\u4e0b\u7ed3\u679c\uff1a<\/p>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p9-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/9c7f386c9857412e8e464f13492d4068~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\u7531\u4e0a\u56fe\u53ef\u77e5\uff0c\u5728\u6df7\u5165\u591a\u4e2a\u7c7b\u578b\u65f6\uff0c\u82e5\u5b58\u5728\u76f8\u540c\u7684\u6210\u5458\uff0c\u4e14\u6210\u5458\u7c7b\u578b\u4e3a\u975e\u57fa\u672c\u6570\u636e\u7c7b\u578b\uff0c\u90a3\u4e48\u662f\u53ef\u4ee5\u6210\u529f\u5408\u5e76\u3002<\/p>\n<h3 data-id=\"heading-52\">\u4e03\u3001TypeScript \u51fd\u6570<\/h3>\n<h4 data-id=\"heading-53\">7.1 TypeScript \u51fd\u6570\u4e0e JavaScript \u51fd\u6570\u7684\u533a\u522b<\/h4>\n<table>\n<thead>\n<tr>\n<th>TypeScript<\/th>\n<th>JavaScript<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\u542b\u6709\u7c7b\u578b<\/td>\n<td>\u65e0\u7c7b\u578b<\/td>\n<\/tr>\n<tr>\n<td>\u7bad\u5934\u51fd\u6570<\/td>\n<td>\u7bad\u5934\u51fd\u6570\uff08ES2015\uff09<\/td>\n<\/tr>\n<tr>\n<td>\u51fd\u6570\u7c7b\u578b<\/td>\n<td>\u65e0\u51fd\u6570\u7c7b\u578b<\/td>\n<\/tr>\n<tr>\n<td>\u5fc5\u586b\u548c\u53ef\u9009\u53c2\u6570<\/td>\n<td>\u6240\u6709\u53c2\u6570\u90fd\u662f\u53ef\u9009\u7684<\/td>\n<\/tr>\n<tr>\n<td>\u9ed8\u8ba4\u53c2\u6570<\/td>\n<td>\u9ed8\u8ba4\u53c2\u6570<\/td>\n<\/tr>\n<tr>\n<td>\u5269\u4f59\u53c2\u6570<\/td>\n<td>\u5269\u4f59\u53c2\u6570<\/td>\n<\/tr>\n<tr>\n<td>\u51fd\u6570\u91cd\u8f7d<\/td>\n<td>\u65e0\u51fd\u6570\u91cd\u8f7d<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 data-id=\"heading-54\">7.2 \u7bad\u5934\u51fd\u6570<\/h4>\n<h5 data-id=\"heading-55\">1.\u5e38\u89c1\u8bed\u6cd5<\/h5>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\">myBooks.forEach(<span class=\"hljs-function\">() =&gt;<\/span> <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'reading'<\/span>));\r\n\r\nmyBooks.forEach(<span class=\"hljs-function\"><span class=\"hljs-params\">title<\/span> =&gt;<\/span> <span class=\"hljs-built_in\">console<\/span>.log(title));\r\n\r\nmyBooks.forEach(<span class=\"hljs-function\">(<span class=\"hljs-params\">title, idx, arr<\/span>) =&gt;<\/span>\r\n  <span class=\"hljs-built_in\">console<\/span>.log(idx + <span class=\"hljs-string\">'-'<\/span> + title);\r\n);\r\n\r\nmyBooks.forEach(<span class=\"hljs-function\">(<span class=\"hljs-params\">title, idx, arr<\/span>) =&gt;<\/span> {\r\n  <span class=\"hljs-built_in\">console<\/span>.log(idx + <span class=\"hljs-string\">'-'<\/span> + title);\r\n});\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-56\">2.\u4f7f\u7528\u793a\u4f8b<\/h5>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ \u672a\u4f7f\u7528\u7bad\u5934\u51fd\u6570<\/span>\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">Book<\/span>() <\/span>{\r\n  <span class=\"hljs-keyword\">let<\/span> self = <span class=\"hljs-built_in\">this<\/span>;\r\n  self.publishDate = <span class=\"hljs-number\">2016<\/span>;\r\n  <span class=\"hljs-built_in\">setInterval<\/span>(<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> () <\/span>{\r\n    <span class=\"hljs-built_in\">console<\/span>.log(self.publishDate);\r\n  }, <span class=\"hljs-number\">1000<\/span>);\r\n}\r\n\r\n<span class=\"hljs-comment\">\/\/ \u4f7f\u7528\u7bad\u5934\u51fd\u6570<\/span>\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">Book<\/span>() <\/span>{\r\n  <span class=\"hljs-built_in\">this<\/span>.publishDate = <span class=\"hljs-number\">2016<\/span>;\r\n  <span class=\"hljs-built_in\">setInterval<\/span>(<span class=\"hljs-function\">() =&gt;<\/span> {\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-built_in\">this<\/span>.publishDate);\r\n  }, <span class=\"hljs-number\">1000<\/span>);\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-57\">7.3 \u53c2\u6570\u7c7b\u578b\u548c\u8fd4\u56de\u7c7b\u578b<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">createUserId<\/span>(<span class=\"hljs-params\">name: <span class=\"hljs-built_in\">string<\/span>, id: <span class=\"hljs-built_in\">number<\/span><\/span>): <span class=\"hljs-title\">string<\/span> <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> name + id;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-58\">7.4 \u51fd\u6570\u7c7b\u578b<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> IdGenerator: <span class=\"hljs-function\">(<span class=\"hljs-params\">chars: <span class=\"hljs-built_in\">string<\/span>, nums: <span class=\"hljs-built_in\">number<\/span><\/span>) =&gt;<\/span> <span class=\"hljs-built_in\">string<\/span>;\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">createUserId<\/span>(<span class=\"hljs-params\">name: <span class=\"hljs-built_in\">string<\/span>, id: <span class=\"hljs-built_in\">number<\/span><\/span>): <span class=\"hljs-title\">string<\/span> <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> name + id;\r\n}\r\n\r\nIdGenerator = createUserId;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-59\">7.5 \u53ef\u9009\u53c2\u6570\u53ca\u9ed8\u8ba4\u53c2\u6570<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ \u53ef\u9009\u53c2\u6570<\/span>\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">createUserId<\/span>(<span class=\"hljs-params\">name: <span class=\"hljs-built_in\">string<\/span>, id: <span class=\"hljs-built_in\">number<\/span>, age?: <span class=\"hljs-built_in\">number<\/span><\/span>): <span class=\"hljs-title\">string<\/span> <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> name + id;\r\n}\r\n\r\n<span class=\"hljs-comment\">\/\/ \u9ed8\u8ba4\u53c2\u6570<\/span>\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">createUserId<\/span>(<span class=\"hljs-params\">\r\n  name: <span class=\"hljs-built_in\">string<\/span> = <span class=\"hljs-string\">\"semlinker\"<\/span>,\r\n  id: <span class=\"hljs-built_in\">number<\/span>,\r\n  age?: <span class=\"hljs-built_in\">number<\/span>\r\n<\/span>): <span class=\"hljs-title\">string<\/span> <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> name + id;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u58f0\u660e\u51fd\u6570\u65f6\uff0c\u53ef\u4ee5\u901a\u8fc7\u00a0<code>?<\/code>\u00a0\u53f7\u6765\u5b9a\u4e49\u53ef\u9009\u53c2\u6570\uff0c\u6bd4\u5982\u00a0<code>age?: number<\/code>\u00a0\u8fd9\u79cd\u5f62\u5f0f\u3002<strong>\u5728\u5b9e\u9645\u4f7f\u7528\u65f6\uff0c\u9700\u8981\u6ce8\u610f\u7684\u662f\u53ef\u9009\u53c2\u6570\u8981\u653e\u5728\u666e\u901a\u53c2\u6570\u7684\u540e\u9762\uff0c\u4e0d\u7136\u4f1a\u5bfc\u81f4\u7f16\u8bd1\u9519\u8bef<\/strong>\u3002<\/p>\n<h4 data-id=\"heading-60\">7.6 \u5269\u4f59\u53c2\u6570<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">push<\/span>(<span class=\"hljs-params\">array, ...items<\/span>) <\/span>{\r\n  items.forEach(<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (<span class=\"hljs-params\">item<\/span>) <\/span>{\r\n    array.push(item);\r\n  });\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> a = [];\r\npush(a, <span class=\"hljs-number\">1<\/span>, <span class=\"hljs-number\">2<\/span>, <span class=\"hljs-number\">3<\/span>);\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-61\">7.7 \u51fd\u6570\u91cd\u8f7d<\/h4>\n<p>\u51fd\u6570\u91cd\u8f7d\u6216\u65b9\u6cd5\u91cd\u8f7d\u662f\u4f7f\u7528\u76f8\u540c\u540d\u79f0\u548c\u4e0d\u540c\u53c2\u6570\u6570\u91cf\u6216\u7c7b\u578b\u521b\u5efa\u591a\u4e2a\u65b9\u6cd5\u7684\u4e00\u79cd\u80fd\u529b\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">add<\/span>(<span class=\"hljs-params\">a: <span class=\"hljs-built_in\">number<\/span>, b: <span class=\"hljs-built_in\">number<\/span><\/span>): <span class=\"hljs-title\">number<\/span><\/span>;\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">add<\/span>(<span class=\"hljs-params\">a: <span class=\"hljs-built_in\">string<\/span>, b: <span class=\"hljs-built_in\">string<\/span><\/span>): <span class=\"hljs-title\">string<\/span><\/span>;\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">add<\/span>(<span class=\"hljs-params\">a: <span class=\"hljs-built_in\">string<\/span>, b: <span class=\"hljs-built_in\">number<\/span><\/span>): <span class=\"hljs-title\">string<\/span><\/span>;\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">add<\/span>(<span class=\"hljs-params\">a: <span class=\"hljs-built_in\">number<\/span>, b: <span class=\"hljs-built_in\">string<\/span><\/span>): <span class=\"hljs-title\">string<\/span><\/span>;\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">add<\/span>(<span class=\"hljs-params\">a: Combinable, b: Combinable<\/span>) <\/span>{\r\n  <span class=\"hljs-comment\">\/\/ type Combinable = string | number;<\/span>\r\n  <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> a === <span class=\"hljs-string\">'string'<\/span> || <span class=\"hljs-keyword\">typeof<\/span> b === <span class=\"hljs-string\">'string'<\/span>) {\r\n    <span class=\"hljs-keyword\">return<\/span> a.toString() + b.toString();\r\n  }\r\n  <span class=\"hljs-keyword\">return<\/span> a + b;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u4ee5\u4e0a\u4ee3\u7801\u4e2d\uff0c\u6211\u4eec\u4e3a add \u51fd\u6570\u63d0\u4f9b\u4e86\u591a\u4e2a\u51fd\u6570\u7c7b\u578b\u5b9a\u4e49\uff0c\u4ece\u800c\u5b9e\u73b0\u51fd\u6570\u7684\u91cd\u8f7d\u3002\u5728 TypeScript \u4e2d\u9664\u4e86\u53ef\u4ee5\u91cd\u8f7d\u666e\u901a\u51fd\u6570\u4e4b\u5916\uff0c\u6211\u4eec\u8fd8\u53ef\u4ee5\u91cd\u8f7d\u7c7b\u4e2d\u7684\u6210\u5458\u65b9\u6cd5\u3002<\/p>\n<p>\u65b9\u6cd5\u91cd\u8f7d\u662f\u6307\u5728\u540c\u4e00\u4e2a\u7c7b\u4e2d\u65b9\u6cd5\u540c\u540d\uff0c\u53c2\u6570\u4e0d\u540c\uff08\u53c2\u6570\u7c7b\u578b\u4e0d\u540c\u3001\u53c2\u6570\u4e2a\u6570\u4e0d\u540c\u6216\u53c2\u6570\u4e2a\u6570\u76f8\u540c\u65f6\u53c2\u6570\u7684\u5148\u540e\u987a\u5e8f\u4e0d\u540c\uff09\uff0c\u8c03\u7528\u65f6\u6839\u636e\u5b9e\u53c2\u7684\u5f62\u5f0f\uff0c\u9009\u62e9\u4e0e\u5b83\u5339\u914d\u7684\u65b9\u6cd5\u6267\u884c\u64cd\u4f5c\u7684\u4e00\u79cd\u6280\u672f\u3002\u6240\u4ee5\u7c7b\u4e2d\u6210\u5458\u65b9\u6cd5\u6ee1\u8db3\u91cd\u8f7d\u7684\u6761\u4ef6\u662f\uff1a\u5728\u540c\u4e00\u4e2a\u7c7b\u4e2d\uff0c\u65b9\u6cd5\u540d\u76f8\u540c\u4e14\u53c2\u6570\u5217\u8868\u4e0d\u540c\u3002\u4e0b\u9762\u6211\u4eec\u6765\u4e3e\u4e00\u4e2a\u6210\u5458\u65b9\u6cd5\u91cd\u8f7d\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Calculator<\/span> <\/span>{\r\n  add(a: <span class=\"hljs-built_in\">number<\/span>, <span class=\"hljs-attr\">b<\/span>: <span class=\"hljs-built_in\">number<\/span>): <span class=\"hljs-built_in\">number<\/span>;\r\n  add(a: <span class=\"hljs-built_in\">string<\/span>, <span class=\"hljs-attr\">b<\/span>: <span class=\"hljs-built_in\">string<\/span>): <span class=\"hljs-built_in\">string<\/span>;\r\n  add(a: <span class=\"hljs-built_in\">string<\/span>, <span class=\"hljs-attr\">b<\/span>: <span class=\"hljs-built_in\">number<\/span>): <span class=\"hljs-built_in\">string<\/span>;\r\n  add(a: <span class=\"hljs-built_in\">number<\/span>, <span class=\"hljs-attr\">b<\/span>: <span class=\"hljs-built_in\">string<\/span>): <span class=\"hljs-built_in\">string<\/span>;\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">add<\/span>(<span class=\"hljs-params\">a: Combinable, b: Combinable<\/span>)<\/span> {\r\n  <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> a === <span class=\"hljs-string\">'string'<\/span> || <span class=\"hljs-keyword\">typeof<\/span> b === <span class=\"hljs-string\">'string'<\/span>) {\r\n    <span class=\"hljs-keyword\">return<\/span> a.toString() + b.toString();\r\n  }\r\n    <span class=\"hljs-keyword\">return<\/span> a + b;\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">const<\/span> calculator = <span class=\"hljs-keyword\">new<\/span> Calculator();\r\n<span class=\"hljs-keyword\">const<\/span> result = calculator.add(<span class=\"hljs-string\">'Semlinker'<\/span>, <span class=\"hljs-string\">' Kakuqo'<\/span>);\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u8fd9\u91cc\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u5f53 TypeScript \u7f16\u8bd1\u5668\u5904\u7406\u51fd\u6570\u91cd\u8f7d\u65f6\uff0c\u5b83\u4f1a\u67e5\u627e\u91cd\u8f7d\u5217\u8868\uff0c\u5c1d\u8bd5\u4f7f\u7528\u7b2c\u4e00\u4e2a\u91cd\u8f7d\u5b9a\u4e49\u3002 \u5982\u679c\u5339\u914d\u7684\u8bdd\u5c31\u4f7f\u7528\u8fd9\u4e2a\u3002 \u56e0\u6b64\uff0c\u5728\u5b9a\u4e49\u91cd\u8f7d\u7684\u65f6\u5019\uff0c\u4e00\u5b9a\u8981\u628a\u6700\u7cbe\u786e\u7684\u5b9a\u4e49\u653e\u5728\u6700\u524d\u9762\u3002\u53e6\u5916\u5728 Calculator \u7c7b\u4e2d\uff0c<code>add(a: Combinable, b: Combinable){ }<\/code>\u00a0\u5e76\u4e0d\u662f\u91cd\u8f7d\u5217\u8868\u7684\u4e00\u90e8\u5206\uff0c\u56e0\u6b64\u5bf9\u4e8e add \u6210\u5458\u65b9\u6cd5\u6765\u8bf4\uff0c\u6211\u4eec\u53ea\u5b9a\u4e49\u4e86\u56db\u4e2a\u91cd\u8f7d\u65b9\u6cd5\u3002<\/p>\n<h3 data-id=\"heading-62\">\u516b\u3001TypeScript \u6570\u7ec4<\/h3>\n<h4 data-id=\"heading-63\">8.1 \u6570\u7ec4\u89e3\u6784<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> x: <span class=\"hljs-built_in\">number<\/span>; <span class=\"hljs-keyword\">let<\/span> y: <span class=\"hljs-built_in\">number<\/span>; <span class=\"hljs-keyword\">let<\/span> z: <span class=\"hljs-built_in\">number<\/span>;\r\n<span class=\"hljs-keyword\">let<\/span> five_array = [<span class=\"hljs-number\">0<\/span>,<span class=\"hljs-number\">1<\/span>,<span class=\"hljs-number\">2<\/span>,<span class=\"hljs-number\">3<\/span>,<span class=\"hljs-number\">4<\/span>];\r\n[x,y,z] = five_array;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-64\">8.2 \u6570\u7ec4\u5c55\u5f00\u8fd0\u7b97\u7b26<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> two_array = [<span class=\"hljs-number\">0<\/span>, <span class=\"hljs-number\">1<\/span>];\r\n<span class=\"hljs-keyword\">let<\/span> five_array = [...two_array, <span class=\"hljs-number\">2<\/span>, <span class=\"hljs-number\">3<\/span>, <span class=\"hljs-number\">4<\/span>];\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-65\">8.3 \u6570\u7ec4\u904d\u5386<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> colors: <span class=\"hljs-built_in\">string<\/span>[] = [<span class=\"hljs-string\">\"red\"<\/span>, <span class=\"hljs-string\">\"green\"<\/span>, <span class=\"hljs-string\">\"blue\"<\/span>];\r\n<span class=\"hljs-keyword\">for<\/span> (<span class=\"hljs-keyword\">let<\/span> i <span class=\"hljs-keyword\">of<\/span> colors) {\r\n  <span class=\"hljs-built_in\">console<\/span>.log(i);\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h3 data-id=\"heading-66\">\u4e5d\u3001TypeScript \u5bf9\u8c61<\/h3>\n<h4 data-id=\"heading-67\">9.1 \u5bf9\u8c61\u89e3\u6784<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> person = {\r\n  <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-string\">\"Semlinker\"<\/span>,\r\n  <span class=\"hljs-attr\">gender<\/span>: <span class=\"hljs-string\">\"Male\"<\/span>,\r\n};\r\n\r\n<span class=\"hljs-keyword\">let<\/span> { name, gender } = person;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-68\">9.2 \u5bf9\u8c61\u5c55\u5f00\u8fd0\u7b97\u7b26<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> person = {\r\n  <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-string\">\"Semlinker\"<\/span>,\r\n  <span class=\"hljs-attr\">gender<\/span>: <span class=\"hljs-string\">\"Male\"<\/span>,\r\n  <span class=\"hljs-attr\">address<\/span>: <span class=\"hljs-string\">\"Xiamen\"<\/span>,\r\n};\r\n\r\n<span class=\"hljs-comment\">\/\/ \u7ec4\u88c5\u5bf9\u8c61<\/span>\r\n<span class=\"hljs-keyword\">let<\/span> personWithAge = { ...person, <span class=\"hljs-attr\">age<\/span>: <span class=\"hljs-number\">33<\/span> };\r\n\r\n<span class=\"hljs-comment\">\/\/ \u83b7\u53d6\u9664\u4e86\u67d0\u4e9b\u9879\u5916\u7684\u5176\u5b83\u9879<\/span>\r\n<span class=\"hljs-keyword\">let<\/span> { name, ...rest } = person;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h3 data-id=\"heading-69\">\u5341\u3001TypeScript \u63a5\u53e3<\/h3>\n<p>\u5728\u9762\u5411\u5bf9\u8c61\u8bed\u8a00\u4e2d\uff0c\u63a5\u53e3\u662f\u4e00\u4e2a\u5f88\u91cd\u8981\u7684\u6982\u5ff5\uff0c\u5b83\u662f\u5bf9\u884c\u4e3a\u7684\u62bd\u8c61\uff0c\u800c\u5177\u4f53\u5982\u4f55\u884c\u52a8\u9700\u8981\u7531\u7c7b\u53bb\u5b9e\u73b0\u3002<\/p>\n<p>TypeScript \u4e2d\u7684\u63a5\u53e3\u662f\u4e00\u4e2a\u975e\u5e38\u7075\u6d3b\u7684\u6982\u5ff5\uff0c\u9664\u4e86\u53ef\u7528\u4e8e<a title=\"https:\/\/ts.xcatliu.com\/advanced\/class-and-interfaces.html#%E7%B1%BB%E5%AE%9E%E7%8E%B0%E6%8E%A5%E5%8F%A3\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fts.xcatliu.com%2Fadvanced%2Fclass-and-interfaces.html%23%25E7%25B1%25BB%25E5%25AE%259E%25E7%258E%25B0%25E6%258E%25A5%25E5%258F%25A3\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">\u5bf9\u7c7b\u7684\u4e00\u90e8\u5206\u884c\u4e3a\u8fdb\u884c\u62bd\u8c61<\/a>\u4ee5\u5916\uff0c\u4e5f\u5e38\u7528\u4e8e\u5bf9\u300c\u5bf9\u8c61\u7684\u5f62\u72b6\uff08Shape\uff09\u300d\u8fdb\u884c\u63cf\u8ff0\u3002<\/p>\n<h4 data-id=\"heading-70\">10.1 \u5bf9\u8c61\u7684\u5f62\u72b6<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Person {\r\n  <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-built_in\">string<\/span>;\r\n  age: <span class=\"hljs-built_in\">number<\/span>;\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> semlinker: Person = {\r\n  <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-string\">\"semlinker\"<\/span>,\r\n  <span class=\"hljs-attr\">age<\/span>: <span class=\"hljs-number\">33<\/span>,\r\n};\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-71\">10.2 \u53ef\u9009 | \u53ea\u8bfb\u5c5e\u6027<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Person {\r\n  <span class=\"hljs-keyword\">readonly<\/span> name: <span class=\"hljs-built_in\">string<\/span>;\r\n  age?: <span class=\"hljs-built_in\">number<\/span>;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u53ea\u8bfb\u5c5e\u6027\u7528\u4e8e\u9650\u5236\u53ea\u80fd\u5728\u5bf9\u8c61\u521a\u521a\u521b\u5efa\u7684\u65f6\u5019\u4fee\u6539\u5176\u503c\u3002\u6b64\u5916 TypeScript \u8fd8\u63d0\u4f9b\u4e86\u00a0<code>ReadonlyArray&lt;T&gt;<\/code>\u00a0\u7c7b\u578b\uff0c\u5b83\u4e0e\u00a0<code>Array&lt;T&gt;<\/code>\u00a0\u76f8\u4f3c\uff0c\u53ea\u662f\u628a\u6240\u6709\u53ef\u53d8\u65b9\u6cd5\u53bb\u6389\u4e86\uff0c\u56e0\u6b64\u53ef\u4ee5\u786e\u4fdd\u6570\u7ec4\u521b\u5efa\u540e\u518d\u4e5f\u4e0d\u80fd\u88ab\u4fee\u6539\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> a: <span class=\"hljs-built_in\">number<\/span>[] = [<span class=\"hljs-number\">1<\/span>, <span class=\"hljs-number\">2<\/span>, <span class=\"hljs-number\">3<\/span>, <span class=\"hljs-number\">4<\/span>];\r\n<span class=\"hljs-keyword\">let<\/span> ro: ReadonlyArray&lt;<span class=\"hljs-built_in\">number<\/span>&gt; = a;\r\nro[<span class=\"hljs-number\">0<\/span>] = <span class=\"hljs-number\">12<\/span>; <span class=\"hljs-comment\">\/\/ error!<\/span>\r\nro.push(<span class=\"hljs-number\">5<\/span>); <span class=\"hljs-comment\">\/\/ error!<\/span>\r\nro.length = <span class=\"hljs-number\">100<\/span>; <span class=\"hljs-comment\">\/\/ error!<\/span>\r\na = ro; <span class=\"hljs-comment\">\/\/ error!<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-72\">10.3 \u4efb\u610f\u5c5e\u6027<\/h4>\n<p>\u6709\u65f6\u5019\u6211\u4eec\u5e0c\u671b\u4e00\u4e2a\u63a5\u53e3\u4e2d\u9664\u4e86\u5305\u542b\u5fc5\u9009\u548c\u53ef\u9009\u5c5e\u6027\u4e4b\u5916\uff0c\u8fd8\u5141\u8bb8\u6709\u5176\u4ed6\u7684\u4efb\u610f\u5c5e\u6027\uff0c\u8fd9\u65f6\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u00a0<strong>\u7d22\u5f15\u7b7e\u540d<\/strong>\u00a0\u7684\u5f62\u5f0f\u6765\u6ee1\u8db3\u4e0a\u8ff0\u8981\u6c42\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Person {\r\n  <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-built_in\">string<\/span>;\r\n  age?: <span class=\"hljs-built_in\">number<\/span>;\r\n  [propName: <span class=\"hljs-built_in\">string<\/span>]: <span class=\"hljs-built_in\">any<\/span>;\r\n}\r\n\r\n<span class=\"hljs-keyword\">const<\/span> p1 = { <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-string\">\"semlinker\"<\/span> };\r\n<span class=\"hljs-keyword\">const<\/span> p2 = { <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-string\">\"lolo\"<\/span>, <span class=\"hljs-attr\">age<\/span>: <span class=\"hljs-number\">5<\/span> };\r\n<span class=\"hljs-keyword\">const<\/span> p3 = { <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-string\">\"kakuqo\"<\/span>, <span class=\"hljs-attr\">sex<\/span>: <span class=\"hljs-number\">1<\/span> }\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-73\">10.4 \u63a5\u53e3\u4e0e\u7c7b\u578b\u522b\u540d\u7684\u533a\u522b<\/h4>\n<h5 data-id=\"heading-74\">1.Objects\/Functions<\/h5>\n<p>\u63a5\u53e3\u548c\u7c7b\u578b\u522b\u540d\u90fd\u53ef\u4ee5\u7528\u6765\u63cf\u8ff0\u5bf9\u8c61\u7684\u5f62\u72b6\u6216\u51fd\u6570\u7b7e\u540d\uff1a<\/p>\n<p><strong>\u63a5\u53e3<\/strong><\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Point {\r\n  <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-built_in\">number<\/span>;\r\n  y: <span class=\"hljs-built_in\">number<\/span>;\r\n}\r\n\r\n<span class=\"hljs-keyword\">interface<\/span> SetPoint {\r\n  (x: <span class=\"hljs-built_in\">number<\/span>, <span class=\"hljs-attr\">y<\/span>: <span class=\"hljs-built_in\">number<\/span>): <span class=\"hljs-built_in\">void<\/span>;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><strong>\u7c7b\u578b\u522b\u540d<\/strong><\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> Point = {\r\n  <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-built_in\">number<\/span>;\r\n  y: <span class=\"hljs-built_in\">number<\/span>;\r\n};\r\n\r\n<span class=\"hljs-keyword\">type<\/span> SetPoint = <span class=\"hljs-function\">(<span class=\"hljs-params\">x: <span class=\"hljs-built_in\">number<\/span>, y: <span class=\"hljs-built_in\">number<\/span><\/span>) =&gt;<\/span> <span class=\"hljs-built_in\">void<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-75\">2.Other Types<\/h5>\n<p>\u4e0e\u63a5\u53e3\u7c7b\u578b\u4e0d\u4e00\u6837\uff0c\u7c7b\u578b\u522b\u540d\u53ef\u4ee5\u7528\u4e8e\u4e00\u4e9b\u5176\u4ed6\u7c7b\u578b\uff0c\u6bd4\u5982\u539f\u59cb\u7c7b\u578b\u3001\u8054\u5408\u7c7b\u578b\u548c\u5143\u7ec4\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ primitive<\/span>\r\n<span class=\"hljs-keyword\">type<\/span> Name = <span class=\"hljs-built_in\">string<\/span>;\r\n\r\n<span class=\"hljs-comment\">\/\/ object<\/span>\r\n<span class=\"hljs-keyword\">type<\/span> PartialPointX = { <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-built_in\">number<\/span>; };\r\n<span class=\"hljs-keyword\">type<\/span> PartialPointY = { <span class=\"hljs-attr\">y<\/span>: <span class=\"hljs-built_in\">number<\/span>; };\r\n\r\n<span class=\"hljs-comment\">\/\/ union<\/span>\r\n<span class=\"hljs-keyword\">type<\/span> PartialPoint = PartialPointX | PartialPointY;\r\n\r\n<span class=\"hljs-comment\">\/\/ tuple<\/span>\r\n<span class=\"hljs-keyword\">type<\/span> Data = [<span class=\"hljs-built_in\">number<\/span>, <span class=\"hljs-built_in\">string<\/span>];\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-76\">3.Extend<\/h5>\n<p>\u63a5\u53e3\u548c\u7c7b\u578b\u522b\u540d\u90fd\u80fd\u591f\u88ab\u6269\u5c55\uff0c\u4f46\u8bed\u6cd5\u6709\u6240\u4e0d\u540c\u3002\u6b64\u5916\uff0c\u63a5\u53e3\u548c\u7c7b\u578b\u522b\u540d\u4e0d\u662f\u4e92\u65a5\u7684\u3002\u63a5\u53e3\u53ef\u4ee5\u6269\u5c55\u7c7b\u578b\u522b\u540d\uff0c\u800c\u53cd\u8fc7\u6765\u662f\u4e0d\u884c\u7684\u3002<\/p>\n<p><strong>Interface extends interface<\/strong><\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> PartialPointX { x: <span class=\"hljs-built_in\">number<\/span>; }\r\n<span class=\"hljs-keyword\">interface<\/span> Point <span class=\"hljs-keyword\">extends<\/span> PartialPointX { \r\n  <span class=\"hljs-attr\">y<\/span>: <span class=\"hljs-built_in\">number<\/span>; \r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><strong>Type alias extends type alias<\/strong><\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> PartialPointX = { <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-built_in\">number<\/span>; };\r\n<span class=\"hljs-keyword\">type<\/span> Point = PartialPointX &amp; { <span class=\"hljs-attr\">y<\/span>: <span class=\"hljs-built_in\">number<\/span>; };\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><strong>Interface extends type alias<\/strong><\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> PartialPointX = { <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-built_in\">number<\/span>; };\r\n<span class=\"hljs-keyword\">interface<\/span> Point <span class=\"hljs-keyword\">extends<\/span> PartialPointX { y: <span class=\"hljs-built_in\">number<\/span>; }\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><strong>Type alias extends interface<\/strong><\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> PartialPointX { x: <span class=\"hljs-built_in\">number<\/span>; }\r\n<span class=\"hljs-keyword\">type<\/span> Point = PartialPointX &amp; { <span class=\"hljs-attr\">y<\/span>: <span class=\"hljs-built_in\">number<\/span>; };\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-77\">4.Implements<\/h5>\n<p>\u7c7b\u53ef\u4ee5\u4ee5\u76f8\u540c\u7684\u65b9\u5f0f\u5b9e\u73b0\u63a5\u53e3\u6216\u7c7b\u578b\u522b\u540d\uff0c\u4f46\u7c7b\u4e0d\u80fd\u5b9e\u73b0\u4f7f\u7528\u7c7b\u578b\u522b\u540d\u5b9a\u4e49\u7684\u8054\u5408\u7c7b\u578b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Point {\r\n  <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-built_in\">number<\/span>;\r\n  y: <span class=\"hljs-built_in\">number<\/span>;\r\n}\r\n\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">SomePoint<\/span> <span class=\"hljs-title\">implements<\/span> <span class=\"hljs-title\">Point<\/span> <\/span>{\r\n  x = <span class=\"hljs-number\">1<\/span>;\r\n  y = <span class=\"hljs-number\">2<\/span>;\r\n}\r\n\r\n<span class=\"hljs-keyword\">type<\/span> Point2 = {\r\n  <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-built_in\">number<\/span>;\r\n  y: <span class=\"hljs-built_in\">number<\/span>;\r\n};\r\n\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">SomePoint2<\/span> <span class=\"hljs-title\">implements<\/span> <span class=\"hljs-title\">Point2<\/span> <\/span>{\r\n  x = <span class=\"hljs-number\">1<\/span>;\r\n  y = <span class=\"hljs-number\">2<\/span>;\r\n}\r\n\r\n<span class=\"hljs-keyword\">type<\/span> PartialPoint = { <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-built_in\">number<\/span>; } | { <span class=\"hljs-attr\">y<\/span>: <span class=\"hljs-built_in\">number<\/span>; };\r\n\r\n<span class=\"hljs-comment\">\/\/ A class can only implement an object type or <\/span>\r\n<span class=\"hljs-comment\">\/\/ intersection of object types with statically known members.<\/span>\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">SomePartialPoint<\/span> <span class=\"hljs-title\">implements<\/span> <span class=\"hljs-title\">PartialPoint<\/span> <\/span>{ <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n  x = <span class=\"hljs-number\">1<\/span>;\r\n  y = <span class=\"hljs-number\">2<\/span>;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-78\">5.Declaration merging<\/h5>\n<p>\u4e0e\u7c7b\u578b\u522b\u540d\u4e0d\u540c\uff0c\u63a5\u53e3\u53ef\u4ee5\u5b9a\u4e49\u591a\u6b21\uff0c\u4f1a\u88ab\u81ea\u52a8\u5408\u5e76\u4e3a\u5355\u4e2a\u63a5\u53e3\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Point { x: <span class=\"hljs-built_in\">number<\/span>; }\r\n<span class=\"hljs-keyword\">interface<\/span> Point { y: <span class=\"hljs-built_in\">number<\/span>; }\r\n\r\n<span class=\"hljs-keyword\">const<\/span> point: Point = { <span class=\"hljs-attr\">x<\/span>: <span class=\"hljs-number\">1<\/span>, <span class=\"hljs-attr\">y<\/span>: <span class=\"hljs-number\">2<\/span> };\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h3 data-id=\"heading-79\">\u5341\u4e00\u3001TypeScript \u7c7b<\/h3>\n<h4 data-id=\"heading-80\">11.1 \u7c7b\u7684\u5c5e\u6027\u4e0e\u65b9\u6cd5<\/h4>\n<p>\u5728\u9762\u5411\u5bf9\u8c61\u8bed\u8a00\u4e2d\uff0c\u7c7b\u662f\u4e00\u79cd\u9762\u5411\u5bf9\u8c61\u8ba1\u7b97\u673a\u7f16\u7a0b\u8bed\u8a00\u7684\u6784\u9020\uff0c\u662f\u521b\u5efa\u5bf9\u8c61\u7684\u84dd\u56fe\uff0c\u63cf\u8ff0\u4e86\u6240\u521b\u5efa\u7684\u5bf9\u8c61\u5171\u540c\u7684\u5c5e\u6027\u548c\u65b9\u6cd5\u3002<\/p>\n<p>\u5728 TypeScript \u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u00a0<code>Class<\/code>\u00a0\u5173\u952e\u5b57\u6765\u5b9a\u4e49\u4e00\u4e2a\u7c7b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Greeter<\/span> <\/span>{\r\n  <span class=\"hljs-comment\">\/\/ \u9759\u6001\u5c5e\u6027<\/span>\r\n  <span class=\"hljs-keyword\">static<\/span> cname: <span class=\"hljs-built_in\">string<\/span> = <span class=\"hljs-string\">\"Greeter\"<\/span>;\r\n  <span class=\"hljs-comment\">\/\/ \u6210\u5458\u5c5e\u6027<\/span>\r\n  greeting: <span class=\"hljs-built_in\">string<\/span>;\r\n\r\n  <span class=\"hljs-comment\">\/\/ \u6784\u9020\u51fd\u6570 - \u6267\u884c\u521d\u59cb\u5316\u64cd\u4f5c<\/span>\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\">message: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> {\r\n    <span class=\"hljs-built_in\">this<\/span>.greeting = message;\r\n  }\r\n\r\n  <span class=\"hljs-comment\">\/\/ \u9759\u6001\u65b9\u6cd5<\/span>\r\n  <span class=\"hljs-keyword\">static<\/span> <span class=\"hljs-function\"><span class=\"hljs-title\">getClassName<\/span>()<\/span> {\r\n    <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-string\">\"Class name is Greeter\"<\/span>;\r\n  }\r\n\r\n  <span class=\"hljs-comment\">\/\/ \u6210\u5458\u65b9\u6cd5<\/span>\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">greet<\/span>()<\/span> {\r\n    <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-string\">\"Hello, \"<\/span> + <span class=\"hljs-built_in\">this<\/span>.greeting;\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> greeter = <span class=\"hljs-keyword\">new<\/span> Greeter(<span class=\"hljs-string\">\"world\"<\/span>);\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u90a3\u4e48\u6210\u5458\u5c5e\u6027\u4e0e\u9759\u6001\u5c5e\u6027\uff0c\u6210\u5458\u65b9\u6cd5\u4e0e\u9759\u6001\u65b9\u6cd5\u6709\u4ec0\u4e48\u533a\u522b\u5462\uff1f\u8fd9\u91cc\u65e0\u9700\u8fc7\u591a\u89e3\u91ca\uff0c\u6211\u4eec\u76f4\u63a5\u770b\u4e00\u4e0b\u7f16\u8bd1\u751f\u6210\u7684 ES5 \u4ee3\u7801\uff1a<\/p>\n<pre><code class=\"hljs language-javascript copyable\" lang=\"javascript\"><span class=\"hljs-meta\">\"use strict\"<\/span>;\r\n<span class=\"hljs-keyword\">var<\/span> Greeter = <span class=\"hljs-comment\">\/** <span class=\"hljs-doctag\">@class <\/span>*\/<\/span> (<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> () <\/span>{\r\n    <span class=\"hljs-comment\">\/\/ \u6784\u9020\u51fd\u6570 - \u6267\u884c\u521d\u59cb\u5316\u64cd\u4f5c<\/span>\r\n    <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">Greeter<\/span>(<span class=\"hljs-params\">message<\/span>) <\/span>{\r\n      <span class=\"hljs-built_in\">this<\/span>.greeting = message;\r\n    }\r\n    <span class=\"hljs-comment\">\/\/ \u9759\u6001\u65b9\u6cd5<\/span>\r\n    Greeter.getClassName = <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> () <\/span>{\r\n      <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-string\">\"Class name is Greeter\"<\/span>;\r\n    };\r\n    <span class=\"hljs-comment\">\/\/ \u6210\u5458\u65b9\u6cd5<\/span>\r\n    Greeter.prototype.greet = <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> () <\/span>{\r\n      <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-string\">\"Hello, \"<\/span> + <span class=\"hljs-built_in\">this<\/span>.greeting;\r\n    };\r\n    <span class=\"hljs-comment\">\/\/ \u9759\u6001\u5c5e\u6027<\/span>\r\n    Greeter.cname = <span class=\"hljs-string\">\"Greeter\"<\/span>;\r\n    <span class=\"hljs-keyword\">return<\/span> Greeter;\r\n}());\r\n<span class=\"hljs-keyword\">var<\/span> greeter = <span class=\"hljs-keyword\">new<\/span> Greeter(<span class=\"hljs-string\">\"world\"<\/span>);\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-81\">11.2 ECMAScript \u79c1\u6709\u5b57\u6bb5<\/h4>\n<p>\u5728 TypeScript 3.8 \u7248\u672c\u5c31\u5f00\u59cb\u652f\u6301<strong>ECMAScript \u79c1\u6709\u5b57\u6bb5<\/strong>\uff0c\u4f7f\u7528\u65b9\u5f0f\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Person<\/span> <\/span>{\r\n  #name: <span class=\"hljs-built_in\">string<\/span>;\r\n\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\">name: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> {\r\n    <span class=\"hljs-built_in\">this<\/span>.#name = name;\r\n  }\r\n\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">greet<\/span>()<\/span> {\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`Hello, my name is <span class=\"hljs-subst\">${<span class=\"hljs-built_in\">this<\/span>.#name}<\/span>!`<\/span>);\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> semlinker = <span class=\"hljs-keyword\">new<\/span> Person(<span class=\"hljs-string\">\"Semlinker\"<\/span>);\r\n\r\nsemlinker.#name;\r\n<span class=\"hljs-comment\">\/\/     ~~~~~<\/span>\r\n<span class=\"hljs-comment\">\/\/ Property '#name' is not accessible outside class 'Person'<\/span>\r\n<span class=\"hljs-comment\">\/\/ because it has a private identifier.<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4e0e\u5e38\u89c4\u5c5e\u6027\uff08\u751a\u81f3\u4f7f\u7528\u00a0<code>private<\/code>\u00a0\u4fee\u9970\u7b26\u58f0\u660e\u7684\u5c5e\u6027\uff09\u4e0d\u540c\uff0c\u79c1\u6709\u5b57\u6bb5\u8981\u7262\u8bb0\u4ee5\u4e0b\u89c4\u5219\uff1a<\/p>\n<ul>\n<li>\u79c1\u6709\u5b57\u6bb5\u4ee5\u00a0<code>#<\/code>\u00a0\u5b57\u7b26\u5f00\u5934\uff0c\u6709\u65f6\u6211\u4eec\u79f0\u4e4b\u4e3a\u79c1\u6709\u540d\u79f0\uff1b<\/li>\n<li>\u6bcf\u4e2a\u79c1\u6709\u5b57\u6bb5\u540d\u79f0\u90fd\u552f\u4e00\u5730\u9650\u5b9a\u4e8e\u5176\u5305\u542b\u7684\u7c7b\uff1b<\/li>\n<li>\u4e0d\u80fd\u5728\u79c1\u6709\u5b57\u6bb5\u4e0a\u4f7f\u7528 TypeScript \u53ef\u8bbf\u95ee\u6027\u4fee\u9970\u7b26\uff08\u5982 public \u6216 private\uff09\uff1b<\/li>\n<li>\u79c1\u6709\u5b57\u6bb5\u4e0d\u80fd\u5728\u5305\u542b\u7684\u7c7b\u4e4b\u5916\u8bbf\u95ee\uff0c\u751a\u81f3\u4e0d\u80fd\u88ab\u68c0\u6d4b\u5230\u3002<\/li>\n<\/ul>\n<h4 data-id=\"heading-82\">11.3 \u8bbf\u95ee\u5668<\/h4>\n<p>\u5728 TypeScript \u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u00a0<code>getter<\/code>\u00a0\u548c\u00a0<code>setter<\/code>\u00a0\u65b9\u6cd5\u6765\u5b9e\u73b0\u6570\u636e\u7684\u5c01\u88c5\u548c\u6709\u6548\u6027\u6821\u9a8c\uff0c\u9632\u6b62\u51fa\u73b0\u5f02\u5e38\u6570\u636e\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">let<\/span> passcode = <span class=\"hljs-string\">\"Hello TypeScript\"<\/span>;\r\n\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Employee<\/span> <\/span>{\r\n  <span class=\"hljs-keyword\">private<\/span> _fullName: <span class=\"hljs-built_in\">string<\/span>;\r\n\r\n  <span class=\"hljs-keyword\">get<\/span> <span class=\"hljs-title\">fullName<\/span>(): <span class=\"hljs-title\">string<\/span> {\r\n    <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-built_in\">this<\/span>._fullName;\r\n  }\r\n\r\n  <span class=\"hljs-keyword\">set<\/span> <span class=\"hljs-title\">fullName<\/span>(<span class=\"hljs-params\">newName: <span class=\"hljs-built_in\">string<\/span><\/span>) {\r\n    <span class=\"hljs-keyword\">if<\/span> (passcode &amp;&amp; passcode == <span class=\"hljs-string\">\"Hello TypeScript\"<\/span>) {\r\n      <span class=\"hljs-built_in\">this<\/span>._fullName = newName;\r\n    } <span class=\"hljs-keyword\">else<\/span> {\r\n      <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"Error: Unauthorized update of employee!\"<\/span>);\r\n    }\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> employee = <span class=\"hljs-keyword\">new<\/span> Employee();\r\nemployee.fullName = <span class=\"hljs-string\">\"Semlinker\"<\/span>;\r\n<span class=\"hljs-keyword\">if<\/span> (employee.fullName) {\r\n  <span class=\"hljs-built_in\">console<\/span>.log(employee.fullName);\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-83\">11.4 \u7c7b\u7684\u7ee7\u627f<\/h4>\n<p>\u7ee7\u627f\uff08Inheritance\uff09\u662f\u4e00\u79cd\u8054\u7ed3\u7c7b\u4e0e\u7c7b\u7684\u5c42\u6b21\u6a21\u578b\u3002\u6307\u7684\u662f\u4e00\u4e2a\u7c7b\uff08\u79f0\u4e3a\u5b50\u7c7b\u3001\u5b50\u63a5\u53e3\uff09\u7ee7\u627f\u53e6\u5916\u7684\u4e00\u4e2a\u7c7b\uff08\u79f0\u4e3a\u7236\u7c7b\u3001\u7236\u63a5\u53e3\uff09\u7684\u529f\u80fd\uff0c\u5e76\u53ef\u4ee5\u589e\u52a0\u5b83\u81ea\u5df1\u7684\u65b0\u529f\u80fd\u7684\u80fd\u529b\uff0c\u7ee7\u627f\u662f\u7c7b\u4e0e\u7c7b\u6216\u8005\u63a5\u53e3\u4e0e\u63a5\u53e3\u4e4b\u95f4\u6700\u5e38\u89c1\u7684\u5173\u7cfb\u3002<\/p>\n<p>\u7ee7\u627f\u662f\u4e00\u79cd\u00a0<a title=\"https:\/\/zh.wikipedia.org\/wiki\/Is-a\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fzh.wikipedia.org%2Fwiki%2FIs-a\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">is-a\u00a0<\/a>\u5173\u7cfb\uff1a<\/p>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p1-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/3c5e414249974e59a7486aa8beaf6746~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\u5728 TypeScript \u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u00a0<code>extends<\/code>\u00a0\u5173\u952e\u5b57\u6765\u5b9e\u73b0\u7ee7\u627f\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Animal<\/span> <\/span>{\r\n  <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-built_in\">string<\/span>;\r\n  \r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\">theName: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> {\r\n    <span class=\"hljs-built_in\">this<\/span>.name = theName;\r\n  }\r\n  \r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">move<\/span>(<span class=\"hljs-params\">distanceInMeters: <span class=\"hljs-built_in\">number<\/span> = <span class=\"hljs-number\">0<\/span><\/span>)<\/span> {\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`<span class=\"hljs-subst\">${<span class=\"hljs-built_in\">this<\/span>.name}<\/span> moved <span class=\"hljs-subst\">${distanceInMeters}<\/span>m.`<\/span>);\r\n  }\r\n}\r\n\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Snake<\/span> <span class=\"hljs-keyword\">extends<\/span> <span class=\"hljs-title\">Animal<\/span> <\/span>{\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\">name: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> {\r\n    <span class=\"hljs-built_in\">super<\/span>(name); <span class=\"hljs-comment\">\/\/ \u8c03\u7528\u7236\u7c7b\u7684\u6784\u9020\u51fd\u6570<\/span>\r\n  }\r\n  \r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">move<\/span>(<span class=\"hljs-params\">distanceInMeters = <span class=\"hljs-number\">5<\/span><\/span>)<\/span> {\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"Slithering...\"<\/span>);\r\n    <span class=\"hljs-built_in\">super<\/span>.move(distanceInMeters);\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> sam = <span class=\"hljs-keyword\">new<\/span> Snake(<span class=\"hljs-string\">\"Sammy the Python\"<\/span>);\r\nsam.move();\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-84\">11.5 \u62bd\u8c61\u7c7b<\/h4>\n<p>\u4f7f\u7528\u00a0<code>abstract<\/code>\u00a0\u5173\u952e\u5b57\u58f0\u660e\u7684\u7c7b\uff0c\u6211\u4eec\u79f0\u4e4b\u4e3a\u62bd\u8c61\u7c7b\u3002\u62bd\u8c61\u7c7b\u4e0d\u80fd\u88ab\u5b9e\u4f8b\u5316\uff0c\u56e0\u4e3a\u5b83\u91cc\u9762\u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u62bd\u8c61\u65b9\u6cd5\u3002\u6240\u8c13\u7684\u62bd\u8c61\u65b9\u6cd5\uff0c\u662f\u6307\u4e0d\u5305\u542b\u5177\u4f53\u5b9e\u73b0\u7684\u65b9\u6cd5\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">abstract<\/span> <span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Person<\/span> <\/span>{\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\"><span class=\"hljs-keyword\">public<\/span> name: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span>{}\r\n\r\n  <span class=\"hljs-keyword\">abstract<\/span> say(words: <span class=\"hljs-built_in\">string<\/span>) :<span class=\"hljs-built_in\">void<\/span>;\r\n}\r\n\r\n<span class=\"hljs-comment\">\/\/ Cannot create an instance of an abstract class.(2511)<\/span>\r\n<span class=\"hljs-keyword\">const<\/span> lolo = <span class=\"hljs-keyword\">new<\/span> Person(); <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u62bd\u8c61\u7c7b\u4e0d\u80fd\u88ab\u76f4\u63a5\u5b9e\u4f8b\u5316\uff0c\u6211\u4eec\u53ea\u80fd\u5b9e\u4f8b\u5316\u5b9e\u73b0\u4e86\u6240\u6709\u62bd\u8c61\u65b9\u6cd5\u7684\u5b50\u7c7b\u3002\u5177\u4f53\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">abstract<\/span> <span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Person<\/span> <\/span>{\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\"><span class=\"hljs-keyword\">public<\/span> name: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span>{}\r\n\r\n  <span class=\"hljs-comment\">\/\/ \u62bd\u8c61\u65b9\u6cd5<\/span>\r\n  <span class=\"hljs-keyword\">abstract<\/span> say(words: <span class=\"hljs-built_in\">string<\/span>) :<span class=\"hljs-built_in\">void<\/span>;\r\n}\r\n\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Developer<\/span> <span class=\"hljs-keyword\">extends<\/span> <span class=\"hljs-title\">Person<\/span> <\/span>{\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\">name: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> {\r\n    <span class=\"hljs-built_in\">super<\/span>(name);\r\n  }\r\n  \r\n  say(words: <span class=\"hljs-built_in\">string<\/span>): <span class=\"hljs-built_in\">void<\/span> {\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`<span class=\"hljs-subst\">${<span class=\"hljs-built_in\">this<\/span>.name}<\/span> says <span class=\"hljs-subst\">${words}<\/span>`<\/span>);\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">const<\/span> lolo = <span class=\"hljs-keyword\">new<\/span> Developer(<span class=\"hljs-string\">\"lolo\"<\/span>);\r\nlolo.say(<span class=\"hljs-string\">\"I love ts!\"<\/span>); <span class=\"hljs-comment\">\/\/ lolo says I love ts!<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-85\">11.6 \u7c7b\u65b9\u6cd5\u91cd\u8f7d<\/h4>\n<p>\u5728\u524d\u9762\u7684\u7ae0\u8282\uff0c\u6211\u4eec\u5df2\u7ecf\u4ecb\u7ecd\u4e86\u51fd\u6570\u91cd\u8f7d\u3002\u5bf9\u4e8e\u7c7b\u7684\u65b9\u6cd5\u6765\u8bf4\uff0c\u5b83\u4e5f\u652f\u6301\u91cd\u8f7d\u3002\u6bd4\u5982\uff0c\u5728\u4ee5\u4e0b\u793a\u4f8b\u4e2d\u6211\u4eec\u91cd\u8f7d\u4e86\u00a0<code>ProductService<\/code>\u00a0\u7c7b\u7684\u00a0<code>getProducts<\/code>\u00a0\u6210\u5458\u65b9\u6cd5\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">ProductService<\/span> <\/span>{\r\n    getProducts(): <span class=\"hljs-built_in\">void<\/span>;\r\n    getProducts(id: <span class=\"hljs-built_in\">number<\/span>): <span class=\"hljs-built_in\">void<\/span>;\r\n    <span class=\"hljs-function\"><span class=\"hljs-title\">getProducts<\/span>(<span class=\"hljs-params\">id?: <span class=\"hljs-built_in\">number<\/span><\/span>)<\/span> {\r\n      <span class=\"hljs-keyword\">if<\/span>(<span class=\"hljs-keyword\">typeof<\/span> id === <span class=\"hljs-string\">'number'<\/span>) {\r\n          <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`\u83b7\u53d6id\u4e3a <span class=\"hljs-subst\">${id}<\/span> \u7684\u4ea7\u54c1\u4fe1\u606f`<\/span>);\r\n      } <span class=\"hljs-keyword\">else<\/span> {\r\n          <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`\u83b7\u53d6\u6240\u6709\u7684\u4ea7\u54c1\u4fe1\u606f`<\/span>);\r\n      }  \r\n    }\r\n}\r\n\r\n<span class=\"hljs-keyword\">const<\/span> productService = <span class=\"hljs-keyword\">new<\/span> ProductService();\r\nproductService.getProducts(<span class=\"hljs-number\">666<\/span>); <span class=\"hljs-comment\">\/\/ \u83b7\u53d6id\u4e3a 666 \u7684\u4ea7\u54c1\u4fe1\u606f<\/span>\r\nproductService.getProducts(); <span class=\"hljs-comment\">\/\/ \u83b7\u53d6\u6240\u6709\u7684\u4ea7\u54c1\u4fe1\u606f <\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h3 data-id=\"heading-86\">\u5341\u4e8c\u3001TypeScript \u6cdb\u578b<\/h3>\n<p>\u8f6f\u4ef6\u5de5\u7a0b\u4e2d\uff0c\u6211\u4eec\u4e0d\u4ec5\u8981\u521b\u5efa\u4e00\u81f4\u7684\u5b9a\u4e49\u826f\u597d\u7684 API\uff0c\u540c\u65f6\u4e5f\u8981\u8003\u8651\u53ef\u91cd\u7528\u6027\u3002 \u7ec4\u4ef6\u4e0d\u4ec5\u80fd\u591f\u652f\u6301\u5f53\u524d\u7684\u6570\u636e\u7c7b\u578b\uff0c\u540c\u65f6\u4e5f\u80fd\u652f\u6301\u672a\u6765\u7684\u6570\u636e\u7c7b\u578b\uff0c\u8fd9\u5728\u521b\u5efa\u5927\u578b\u7cfb\u7edf\u65f6\u4e3a\u4f60\u63d0\u4f9b\u4e86\u5341\u5206\u7075\u6d3b\u7684\u529f\u80fd\u3002<\/p>\n<p><strong>\u5728\u50cf C# \u548c Java \u8fd9\u6837\u7684\u8bed\u8a00\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528\u6cdb\u578b\u6765\u521b\u5efa\u53ef\u91cd\u7528\u7684\u7ec4\u4ef6\uff0c\u4e00\u4e2a\u7ec4\u4ef6\u53ef\u4ee5\u652f\u6301\u591a\u79cd\u7c7b\u578b\u7684\u6570\u636e\u3002 \u8fd9\u6837\u7528\u6237\u5c31\u53ef\u4ee5\u4ee5\u81ea\u5df1\u7684\u6570\u636e\u7c7b\u578b\u6765\u4f7f\u7528\u7ec4\u4ef6\u3002<\/strong><\/p>\n<p>\u8bbe\u8ba1\u6cdb\u578b\u7684\u5173\u952e\u76ee\u7684\u662f\u5728\u6210\u5458\u4e4b\u95f4\u63d0\u4f9b\u6709\u610f\u4e49\u7684\u7ea6\u675f\uff0c\u8fd9\u4e9b\u6210\u5458\u53ef\u4ee5\u662f\uff1a\u7c7b\u7684\u5b9e\u4f8b\u6210\u5458\u3001\u7c7b\u7684\u65b9\u6cd5\u3001\u51fd\u6570\u53c2\u6570\u548c\u51fd\u6570\u8fd4\u56de\u503c\u3002<\/p>\n<p>\u6cdb\u578b\uff08Generics\uff09\u662f\u5141\u8bb8\u540c\u4e00\u4e2a\u51fd\u6570\u63a5\u53d7\u4e0d\u540c\u7c7b\u578b\u53c2\u6570\u7684\u4e00\u79cd\u6a21\u677f\u3002\u76f8\u6bd4\u4e8e\u4f7f\u7528 any \u7c7b\u578b\uff0c\u4f7f\u7528\u6cdb\u578b\u6765\u521b\u5efa\u53ef\u590d\u7528\u7684\u7ec4\u4ef6\u8981\u66f4\u597d\uff0c\u56e0\u4e3a\u6cdb\u578b\u4f1a\u4fdd\u7559\u53c2\u6570\u7c7b\u578b\u3002<\/p>\n<h4 data-id=\"heading-87\">12.1 \u6cdb\u578b\u8bed\u6cd5<\/h4>\n<p>\u5bf9\u4e8e\u521a\u63a5\u89e6 TypeScript \u6cdb\u578b\u7684\u8bfb\u8005\u6765\u8bf4\uff0c\u9996\u6b21\u770b\u5230\u00a0<code>&lt;T&gt;<\/code>\u00a0\u8bed\u6cd5\u4f1a\u611f\u5230\u964c\u751f\u3002\u5176\u5b9e\u5b83\u6ca1\u6709\u4ec0\u4e48\u7279\u522b\uff0c\u5c31\u50cf\u4f20\u9012\u53c2\u6570\u4e00\u6837\uff0c\u6211\u4eec\u4f20\u9012\u4e86\u6211\u4eec\u60f3\u8981\u7528\u4e8e\u7279\u5b9a\u51fd\u6570\u8c03\u7528\u7684\u7c7b\u578b\u3002<\/p>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p9-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/f295fd4930824a3ea0f015c81aa568e7~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\u53c2\u8003\u4e0a\u9762\u7684\u56fe\u7247\uff0c\u5f53\u6211\u4eec\u8c03\u7528\u00a0<code>identity&lt;Number&gt;(1)<\/code>\u00a0\uff0c<code>Number<\/code>\u00a0\u7c7b\u578b\u5c31\u50cf\u53c2\u6570\u00a0<code>1<\/code>\u00a0\u4e00\u6837\uff0c\u5b83\u5c06\u5728\u51fa\u73b0\u00a0<code>T<\/code>\u00a0\u7684\u4efb\u4f55\u4f4d\u7f6e\u586b\u5145\u8be5\u7c7b\u578b\u3002\u56fe\u4e2d\u00a0<code>&lt;T&gt;<\/code>\u00a0\u5185\u90e8\u7684\u00a0<code>T<\/code>\u00a0\u88ab\u79f0\u4e3a\u7c7b\u578b\u53d8\u91cf\uff0c\u5b83\u662f\u6211\u4eec\u5e0c\u671b\u4f20\u9012\u7ed9 identity \u51fd\u6570\u7684\u7c7b\u578b\u5360\u4f4d\u7b26\uff0c\u540c\u65f6\u5b83\u88ab\u5206\u914d\u7ed9\u00a0<code>value<\/code>\u00a0\u53c2\u6570\u7528\u6765\u4ee3\u66ff\u5b83\u7684\u7c7b\u578b\uff1a\u6b64\u65f6\u00a0<code>T<\/code>\u00a0\u5145\u5f53\u7684\u662f\u7c7b\u578b\uff0c\u800c\u4e0d\u662f\u7279\u5b9a\u7684 Number \u7c7b\u578b\u3002<\/p>\n<p>\u5176\u4e2d\u00a0<code>T<\/code>\u00a0\u4ee3\u8868\u00a0<strong>Type<\/strong>\uff0c\u5728\u5b9a\u4e49\u6cdb\u578b\u65f6\u901a\u5e38\u7528\u4f5c\u7b2c\u4e00\u4e2a\u7c7b\u578b\u53d8\u91cf\u540d\u79f0\u3002\u4f46\u5b9e\u9645\u4e0a\u00a0<code>T<\/code>\u00a0\u53ef\u4ee5\u7528\u4efb\u4f55\u6709\u6548\u540d\u79f0\u4ee3\u66ff\u3002\u9664\u4e86\u00a0<code>T<\/code>\u00a0\u4e4b\u5916\uff0c\u4ee5\u4e0b\u662f\u5e38\u89c1\u6cdb\u578b\u53d8\u91cf\u4ee3\u8868\u7684\u610f\u601d\uff1a<\/p>\n<ul>\n<li>K\uff08Key\uff09\uff1a\u8868\u793a\u5bf9\u8c61\u4e2d\u7684\u952e\u7c7b\u578b\uff1b<\/li>\n<li>V\uff08Value\uff09\uff1a\u8868\u793a\u5bf9\u8c61\u4e2d\u7684\u503c\u7c7b\u578b\uff1b<\/li>\n<li>E\uff08Element\uff09\uff1a\u8868\u793a\u5143\u7d20\u7c7b\u578b\u3002<\/li>\n<\/ul>\n<p>\u5176\u5b9e\u5e76\u4e0d\u662f\u53ea\u80fd\u5b9a\u4e49\u4e00\u4e2a\u7c7b\u578b\u53d8\u91cf\uff0c\u6211\u4eec\u53ef\u4ee5\u5f15\u5165\u5e0c\u671b\u5b9a\u4e49\u7684\u4efb\u4f55\u6570\u91cf\u7684\u7c7b\u578b\u53d8\u91cf\u3002\u6bd4\u5982\u6211\u4eec\u5f15\u5165\u4e00\u4e2a\u65b0\u7684\u7c7b\u578b\u53d8\u91cf\u00a0<code>U<\/code>\uff0c\u7528\u4e8e\u6269\u5c55\u6211\u4eec\u5b9a\u4e49\u7684\u00a0<code>identity<\/code>\u00a0\u51fd\u6570\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">identity<\/span> &lt;<span class=\"hljs-title\">T<\/span>, <span class=\"hljs-title\">U<\/span>&gt;(<span class=\"hljs-params\">value: T, message: U<\/span>) : <span class=\"hljs-title\">T<\/span> <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(message);\r\n  <span class=\"hljs-keyword\">return<\/span> value;\r\n}\r\n\r\n<span class=\"hljs-built_in\">console<\/span>.log(identity&lt;<span class=\"hljs-built_in\">Number<\/span>, <span class=\"hljs-built_in\">string<\/span>&gt;(<span class=\"hljs-number\">68<\/span>, <span class=\"hljs-string\">\"Semlinker\"<\/span>));\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p1-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/8c01377aef194da9bbf05e7cf6910a30~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\u9664\u4e86\u4e3a\u7c7b\u578b\u53d8\u91cf\u663e\u5f0f\u8bbe\u5b9a\u503c\u4e4b\u5916\uff0c\u4e00\u79cd\u66f4\u5e38\u89c1\u7684\u505a\u6cd5\u662f\u4f7f\u7f16\u8bd1\u5668\u81ea\u52a8\u9009\u62e9\u8fd9\u4e9b\u7c7b\u578b\uff0c\u4ece\u800c\u4f7f\u4ee3\u7801\u66f4\u7b80\u6d01\u3002\u6211\u4eec\u53ef\u4ee5\u5b8c\u5168\u7701\u7565\u5c16\u62ec\u53f7\uff0c\u6bd4\u5982\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">identity<\/span> &lt;<span class=\"hljs-title\">T<\/span>, <span class=\"hljs-title\">U<\/span>&gt;(<span class=\"hljs-params\">value: T, message: U<\/span>) : <span class=\"hljs-title\">T<\/span> <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(message);\r\n  <span class=\"hljs-keyword\">return<\/span> value;\r\n}\r\n\r\n<span class=\"hljs-built_in\">console<\/span>.log(identity(<span class=\"hljs-number\">68<\/span>, <span class=\"hljs-string\">\"Semlinker\"<\/span>));\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5bf9\u4e8e\u4e0a\u8ff0\u4ee3\u7801\uff0c\u7f16\u8bd1\u5668\u8db3\u591f\u806a\u660e\uff0c\u80fd\u591f\u77e5\u9053\u6211\u4eec\u7684\u53c2\u6570\u7c7b\u578b\uff0c\u5e76\u5c06\u5b83\u4eec\u8d4b\u503c\u7ed9 T \u548c U\uff0c\u800c\u4e0d\u9700\u8981\u5f00\u53d1\u4eba\u5458\u663e\u5f0f\u6307\u5b9a\u5b83\u4eec\u3002<\/p>\n<h4 data-id=\"heading-88\">12.2 \u6cdb\u578b\u63a5\u53e3<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> GenericIdentityFn&lt;T&gt; {\r\n  (arg: T): T;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-89\">12.3 \u6cdb\u578b\u7c7b<\/h4>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">GenericNumber<\/span>&lt;<span class=\"hljs-title\">T<\/span>&gt; <\/span>{\r\n  <span class=\"hljs-attr\">zeroValue<\/span>: T;\r\n  add: <span class=\"hljs-function\">(<span class=\"hljs-params\">x: T, y: T<\/span>) =&gt;<\/span> T;\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> myGenericNumber = <span class=\"hljs-keyword\">new<\/span> GenericNumber&lt;<span class=\"hljs-built_in\">number<\/span>&gt;();\r\nmyGenericNumber.zeroValue = <span class=\"hljs-number\">0<\/span>;\r\nmyGenericNumber.add = <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (<span class=\"hljs-params\">x, y<\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> x + y;\r\n};\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-90\">12.4 \u6cdb\u578b\u5de5\u5177\u7c7b\u578b<\/h4>\n<p>\u4e3a\u4e86\u65b9\u4fbf\u5f00\u53d1\u8005 TypeScript \u5185\u7f6e\u4e86\u4e00\u4e9b\u5e38\u7528\u7684\u5de5\u5177\u7c7b\u578b\uff0c\u6bd4\u5982 Partial\u3001Required\u3001Readonly\u3001Record \u548c ReturnType \u7b49\u3002\u51fa\u4e8e\u7bc7\u5e45\u8003\u8651\uff0c\u8fd9\u91cc\u6211\u4eec\u53ea\u7b80\u5355\u4ecb\u7ecd Partial \u5de5\u5177\u7c7b\u578b\u3002\u4e0d\u8fc7\u5728\u5177\u4f53\u4ecb\u7ecd\u4e4b\u524d\uff0c\u6211\u4eec\u5f97\u5148\u4ecb\u7ecd\u4e00\u4e9b\u76f8\u5173\u7684\u57fa\u7840\u77e5\u8bc6\uff0c\u65b9\u4fbf\u8bfb\u8005\u81ea\u884c\u5b66\u4e60\u5176\u5b83\u7684\u5de5\u5177\u7c7b\u578b\u3002<\/p>\n<h5 data-id=\"heading-91\">1.typeof<\/h5>\n<p>\u5728 TypeScript \u4e2d\uff0c<code>typeof<\/code>\u00a0\u64cd\u4f5c\u7b26\u53ef\u4ee5\u7528\u6765\u83b7\u53d6\u4e00\u4e2a\u53d8\u91cf\u58f0\u660e\u6216\u5bf9\u8c61\u7684\u7c7b\u578b\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Person {\r\n  <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-built_in\">string<\/span>;\r\n  age: <span class=\"hljs-built_in\">number<\/span>;\r\n}\r\n\r\n<span class=\"hljs-keyword\">const<\/span> sem: Person = { <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-string\">'semlinker'<\/span>, <span class=\"hljs-attr\">age<\/span>: <span class=\"hljs-number\">33<\/span> };\r\n<span class=\"hljs-keyword\">type<\/span> Sem= <span class=\"hljs-keyword\">typeof<\/span> sem; <span class=\"hljs-comment\">\/\/ -&gt; Person<\/span>\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">toArray<\/span>(<span class=\"hljs-params\">x: <span class=\"hljs-built_in\">number<\/span><\/span>): <span class=\"hljs-title\">Array<\/span>&lt;<span class=\"hljs-title\">number<\/span>&gt; <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> [x];\r\n}\r\n\r\n<span class=\"hljs-keyword\">type<\/span> Func = <span class=\"hljs-keyword\">typeof<\/span> toArray; <span class=\"hljs-comment\">\/\/ -&gt; (x: number) =&gt; number[]<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-92\">2.keyof<\/h5>\n<p><code>keyof<\/code>\u00a0\u64cd\u4f5c\u7b26\u662f\u5728 TypeScript 2.1 \u7248\u672c\u5f15\u5165\u7684\uff0c\u8be5\u64cd\u4f5c\u7b26\u53ef\u4ee5\u7528\u4e8e\u83b7\u53d6\u67d0\u79cd\u7c7b\u578b\u7684\u6240\u6709\u952e\uff0c\u5176\u8fd4\u56de\u7c7b\u578b\u662f\u8054\u5408\u7c7b\u578b\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Person {\r\n  <span class=\"hljs-attr\">name<\/span>: <span class=\"hljs-built_in\">string<\/span>;\r\n  age: <span class=\"hljs-built_in\">number<\/span>;\r\n}\r\n\r\n<span class=\"hljs-keyword\">type<\/span> K1 = keyof Person; <span class=\"hljs-comment\">\/\/ \"name\" | \"age\"<\/span>\r\n<span class=\"hljs-keyword\">type<\/span> K2 = keyof Person[]; <span class=\"hljs-comment\">\/\/ \"length\" | \"toString\" | \"pop\" | \"push\" | \"concat\" | \"join\" <\/span>\r\n<span class=\"hljs-keyword\">type<\/span> K3 = keyof { [x: <span class=\"hljs-built_in\">string<\/span>]: Person };  <span class=\"hljs-comment\">\/\/ string | number<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728 TypeScript \u4e2d\u652f\u6301\u4e24\u79cd\u7d22\u5f15\u7b7e\u540d\uff0c\u6570\u5b57\u7d22\u5f15\u548c\u5b57\u7b26\u4e32\u7d22\u5f15\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> StringArray {\r\n  <span class=\"hljs-comment\">\/\/ \u5b57\u7b26\u4e32\u7d22\u5f15 -&gt; keyof StringArray =&gt; string | number<\/span>\r\n  [index: <span class=\"hljs-built_in\">string<\/span>]: <span class=\"hljs-built_in\">string<\/span>; \r\n}\r\n\r\n<span class=\"hljs-keyword\">interface<\/span> StringArray1 {\r\n  <span class=\"hljs-comment\">\/\/ \u6570\u5b57\u7d22\u5f15 -&gt; keyof StringArray1 =&gt; number<\/span>\r\n  [index: <span class=\"hljs-built_in\">number<\/span>]: <span class=\"hljs-built_in\">string<\/span>;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4e3a\u4e86\u540c\u65f6\u652f\u6301\u4e24\u79cd\u7d22\u5f15\u7c7b\u578b\uff0c\u5c31\u5f97\u8981\u6c42\u6570\u5b57\u7d22\u5f15\u7684\u8fd4\u56de\u503c\u5fc5\u987b\u662f\u5b57\u7b26\u4e32\u7d22\u5f15\u8fd4\u56de\u503c\u7684\u5b50\u7c7b\u3002<strong>\u5176\u4e2d\u7684\u539f\u56e0\u5c31\u662f\u5f53\u4f7f\u7528\u6570\u503c\u7d22\u5f15\u65f6\uff0cJavaScript \u5728\u6267\u884c\u7d22\u5f15\u64cd\u4f5c\u65f6\uff0c\u4f1a\u5148\u628a\u6570\u503c\u7d22\u5f15\u5148\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\u7d22\u5f15<\/strong>\u3002\u6240\u4ee5\u00a0<code>keyof { [x: string]: Person }<\/code>\u00a0\u7684\u7ed3\u679c\u4f1a\u8fd4\u56de\u00a0<code>string | number<\/code>\u3002<\/p>\n<h5 data-id=\"heading-93\">3.in<\/h5>\n<p><code>in<\/code>\u00a0\u7528\u6765\u904d\u5386\u679a\u4e3e\u7c7b\u578b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> Keys = <span class=\"hljs-string\">\"a\"<\/span> | <span class=\"hljs-string\">\"b\"<\/span> | <span class=\"hljs-string\">\"c\"<\/span>\r\n\r\n<span class=\"hljs-keyword\">type<\/span> Obj =  {\r\n  [p <span class=\"hljs-keyword\">in<\/span> Keys]: <span class=\"hljs-built_in\">any<\/span>\r\n} <span class=\"hljs-comment\">\/\/ -&gt; { a: any, b: any, c: any }<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-94\">4.infer<\/h5>\n<p>\u5728\u6761\u4ef6\u7c7b\u578b\u8bed\u53e5\u4e2d\uff0c\u53ef\u4ee5\u7528\u00a0<code>infer<\/code>\u00a0\u58f0\u660e\u4e00\u4e2a\u7c7b\u578b\u53d8\u91cf\u5e76\u4e14\u5bf9\u5b83\u8fdb\u884c\u4f7f\u7528\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">type<\/span> ReturnType&lt;T&gt; = T <span class=\"hljs-keyword\">extends<\/span> (\r\n  ...args: <span class=\"hljs-built_in\">any<\/span>[]\r\n) =&gt; infer R ? R : <span class=\"hljs-built_in\">any<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a\u4ee3\u7801\u4e2d\u00a0<code>infer R<\/code>\u00a0\u5c31\u662f\u58f0\u660e\u4e00\u4e2a\u53d8\u91cf\u6765\u627f\u8f7d\u4f20\u5165\u51fd\u6570\u7b7e\u540d\u7684\u8fd4\u56de\u503c\u7c7b\u578b\uff0c\u7b80\u5355\u8bf4\u5c31\u662f\u7528\u5b83\u53d6\u5230\u51fd\u6570\u8fd4\u56de\u503c\u7684\u7c7b\u578b\u65b9\u4fbf\u4e4b\u540e\u4f7f\u7528\u3002<\/p>\n<h5 data-id=\"heading-95\">5.extends<\/h5>\n<p>\u6709\u65f6\u5019\u6211\u4eec\u5b9a\u4e49\u7684\u6cdb\u578b\u4e0d\u60f3\u8fc7\u4e8e\u7075\u6d3b\u6216\u8005\u8bf4\u60f3\u7ee7\u627f\u67d0\u4e9b\u7c7b\u7b49\uff0c\u53ef\u4ee5\u901a\u8fc7 extends \u5173\u952e\u5b57\u6dfb\u52a0\u6cdb\u578b\u7ea6\u675f\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Lengthwise {\r\n  <span class=\"hljs-attr\">length<\/span>: <span class=\"hljs-built_in\">number<\/span>;\r\n}\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">loggingIdentity<\/span>&lt;<span class=\"hljs-title\">T<\/span> <span class=\"hljs-title\">extends<\/span> <span class=\"hljs-title\">Lengthwise<\/span>&gt;(<span class=\"hljs-params\">arg: T<\/span>): <span class=\"hljs-title\">T<\/span> <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(arg.length);\r\n  <span class=\"hljs-keyword\">return<\/span> arg;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u73b0\u5728\u8fd9\u4e2a\u6cdb\u578b\u51fd\u6570\u88ab\u5b9a\u4e49\u4e86\u7ea6\u675f\uff0c\u56e0\u6b64\u5b83\u4e0d\u518d\u662f\u9002\u7528\u4e8e\u4efb\u610f\u7c7b\u578b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\">loggingIdentity(<span class=\"hljs-number\">3<\/span>);  <span class=\"hljs-comment\">\/\/ Error, number doesn't have a .length property<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u8fd9\u65f6\u6211\u4eec\u9700\u8981\u4f20\u5165\u7b26\u5408\u7ea6\u675f\u7c7b\u578b\u7684\u503c\uff0c\u5fc5\u987b\u5305\u542b\u5fc5\u987b\u7684\u5c5e\u6027\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\">loggingIdentity({<span class=\"hljs-attr\">length<\/span>: <span class=\"hljs-number\">10<\/span>, <span class=\"hljs-attr\">value<\/span>: <span class=\"hljs-number\">3<\/span>});\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h5 data-id=\"heading-96\">6.Partial<\/h5>\n<p><code>Partial&lt;T&gt;<\/code>\u00a0\u7684\u4f5c\u7528\u5c31\u662f\u5c06\u67d0\u4e2a\u7c7b\u578b\u91cc\u7684\u5c5e\u6027\u5168\u90e8\u53d8\u4e3a\u53ef\u9009\u9879\u00a0<code>?<\/code>\u3002<\/p>\n<p><strong>\u5b9a\u4e49\uff1a<\/strong><\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/**\r\n * node_modules\/typescript\/lib\/lib.es5.d.ts\r\n * Make all properties in T optional\r\n *\/<\/span>\r\n<span class=\"hljs-keyword\">type<\/span> Partial&lt;T&gt; = {\r\n  [P <span class=\"hljs-keyword\">in<\/span> keyof T]?: T[P];\r\n};\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u4ee5\u4e0a\u4ee3\u7801\u4e2d\uff0c\u9996\u5148\u901a\u8fc7\u00a0<code>keyof T<\/code>\u00a0\u62ff\u5230\u00a0<code>T<\/code>\u00a0\u7684\u6240\u6709\u5c5e\u6027\u540d\uff0c\u7136\u540e\u4f7f\u7528\u00a0<code>in<\/code>\u00a0\u8fdb\u884c\u904d\u5386\uff0c\u5c06\u503c\u8d4b\u7ed9\u00a0<code>P<\/code>\uff0c\u6700\u540e\u901a\u8fc7\u00a0<code>T[P]<\/code>\u00a0\u53d6\u5f97\u76f8\u5e94\u7684\u5c5e\u6027\u503c\u3002\u4e2d\u95f4\u7684\u00a0<code>?<\/code>\u00a0\u53f7\uff0c\u7528\u4e8e\u5c06\u6240\u6709\u5c5e\u6027\u53d8\u4e3a\u53ef\u9009\u3002<\/p>\n<p><strong>\u793a\u4f8b\uff1a<\/strong><\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">interface<\/span> Todo {\r\n  <span class=\"hljs-attr\">title<\/span>: <span class=\"hljs-built_in\">string<\/span>;\r\n  description: <span class=\"hljs-built_in\">string<\/span>;\r\n}\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">updateTodo<\/span>(<span class=\"hljs-params\">todo: Todo, fieldsToUpdate: Partial&lt;Todo&gt;<\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> { ...todo, ...fieldsToUpdate };\r\n}\r\n\r\n<span class=\"hljs-keyword\">const<\/span> todo1 = {\r\n  <span class=\"hljs-attr\">title<\/span>: <span class=\"hljs-string\">\"Learn TS\"<\/span>,\r\n  <span class=\"hljs-attr\">description<\/span>: <span class=\"hljs-string\">\"Learn TypeScript\"<\/span>,\r\n};\r\n\r\n<span class=\"hljs-keyword\">const<\/span> todo2 = updateTodo(todo1, {\r\n  <span class=\"hljs-attr\">description<\/span>: <span class=\"hljs-string\">\"Learn TypeScript Enum\"<\/span>,\r\n});\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5728\u4e0a\u9762\u7684\u00a0<code>updateTodo<\/code>\u00a0\u65b9\u6cd5\u4e2d\uff0c\u6211\u4eec\u5229\u7528\u00a0<code>Partial&lt;T&gt;<\/code>\u00a0\u5de5\u5177\u7c7b\u578b\uff0c\u5b9a\u4e49\u00a0<code>fieldsToUpdate<\/code>\u00a0\u7684\u7c7b\u578b\u4e3a\u00a0<code>Partial&lt;Todo&gt;<\/code>\uff0c\u5373\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\">{\r\n   title?: <span class=\"hljs-built_in\">string<\/span> | <span class=\"hljs-literal\">undefined<\/span>;\r\n   description?: <span class=\"hljs-built_in\">string<\/span> | <span class=\"hljs-literal\">undefined<\/span>;\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h3 data-id=\"heading-97\">\u5341\u4e09\u3001TypeScript \u88c5\u9970\u5668<\/h3>\n<h4 data-id=\"heading-98\">13.1 \u88c5\u9970\u5668\u662f\u4ec0\u4e48<\/h4>\n<ul>\n<li>\u5b83\u662f\u4e00\u4e2a\u8868\u8fbe\u5f0f<\/li>\n<li>\u8be5\u8868\u8fbe\u5f0f\u88ab\u6267\u884c\u540e\uff0c\u8fd4\u56de\u4e00\u4e2a\u51fd\u6570<\/li>\n<li>\u51fd\u6570\u7684\u5165\u53c2\u5206\u522b\u4e3a target\u3001name \u548c descriptor<\/li>\n<li>\u6267\u884c\u8be5\u51fd\u6570\u540e\uff0c\u53ef\u80fd\u8fd4\u56de descriptor \u5bf9\u8c61\uff0c\u7528\u4e8e\u914d\u7f6e target \u5bf9\u8c61<\/li>\n<\/ul>\n<h4 data-id=\"heading-99\">13.2 \u88c5\u9970\u5668\u7684\u5206\u7c7b<\/h4>\n<ul>\n<li>\u7c7b\u88c5\u9970\u5668\uff08Class decorators\uff09<\/li>\n<li>\u5c5e\u6027\u88c5\u9970\u5668\uff08Property decorators\uff09<\/li>\n<li>\u65b9\u6cd5\u88c5\u9970\u5668\uff08Method decorators\uff09<\/li>\n<li>\u53c2\u6570\u88c5\u9970\u5668\uff08Parameter decorators\uff09<\/li>\n<\/ul>\n<p>\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u82e5\u8981\u542f\u7528\u5b9e\u9a8c\u6027\u7684\u88c5\u9970\u5668\u7279\u6027\uff0c\u4f60\u5fc5\u987b\u5728\u547d\u4ee4\u884c\u6216\u00a0<code>tsconfig.json<\/code>\u00a0\u91cc\u542f\u7528\u00a0<code>experimentalDecorators<\/code>\u00a0\u7f16\u8bd1\u5668\u9009\u9879\uff1a<\/p>\n<p><strong>\u547d\u4ee4\u884c<\/strong>\uff1a<\/p>\n<pre><code class=\"hljs language-shell copyable\" lang=\"shell\">tsc --target ES5 --experimentalDecorators\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p><strong>tsconfig.json<\/strong>\uff1a<\/p>\n<pre><code class=\"hljs language-json copyable\" lang=\"json\">{\r\n  <span class=\"hljs-attr\">\"compilerOptions\"<\/span>: {\r\n     <span class=\"hljs-attr\">\"target\"<\/span>: <span class=\"hljs-string\">\"ES5\"<\/span>,\r\n     <span class=\"hljs-attr\">\"experimentalDecorators\"<\/span>: <span class=\"hljs-literal\">true<\/span>\r\n   }\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-100\">13.3 \u7c7b\u88c5\u9970\u5668<\/h4>\n<p>\u7c7b\u88c5\u9970\u5668\u58f0\u660e\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">declare<\/span> <span class=\"hljs-keyword\">type<\/span> ClassDecorator = <span class=\"xml\"><span class=\"hljs-tag\">&lt;<span class=\"hljs-name\">TFunction<\/span> <span class=\"hljs-attr\">extends<\/span> <span class=\"hljs-attr\">Function<\/span>&gt;<\/span>(\r\n  target: TFunction\r\n) =&gt; TFunction | void;\r\n<\/span><span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u7c7b\u88c5\u9970\u5668\u987e\u540d\u601d\u4e49\uff0c\u5c31\u662f\u7528\u6765\u88c5\u9970\u7c7b\u7684\u3002\u5b83\u63a5\u6536\u4e00\u4e2a\u53c2\u6570\uff1a<\/p>\n<ul>\n<li>target: TFunction &#8211; \u88ab\u88c5\u9970\u7684\u7c7b<\/li>\n<\/ul>\n<p>\u770b\u5b8c\u7b2c\u4e00\u773c\u540e\uff0c\u662f\u4e0d\u662f\u611f\u89c9\u90fd\u4e0d\u597d\u4e86\u3002\u6ca1\u4e8b\uff0c\u6211\u4eec\u9a6c\u4e0a\u6765\u4e2a\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">Greeter<\/span>(<span class=\"hljs-params\">target: <span class=\"hljs-built_in\">Function<\/span><\/span>): <span class=\"hljs-title\">void<\/span> <\/span>{\r\n  target.prototype.greet = <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (): <span class=\"hljs-title\">void<\/span> <\/span>{\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"Hello Semlinker!\"<\/span>);\r\n  };\r\n}\r\n\r\n<span class=\"hljs-meta\">@Greeter<\/span>\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Greeting<\/span> <\/span>{\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>()<\/span> {\r\n    <span class=\"hljs-comment\">\/\/ \u5185\u90e8\u5b9e\u73b0<\/span>\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> myGreeting = <span class=\"hljs-keyword\">new<\/span> Greeting();\r\n(myGreeting <span class=\"hljs-keyword\">as<\/span> <span class=\"hljs-built_in\">any<\/span>).greet(); <span class=\"hljs-comment\">\/\/ console output: 'Hello Semlinker!';<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0c\u6211\u4eec\u5b9a\u4e49\u4e86\u00a0<code>Greeter<\/code>\u00a0\u7c7b\u88c5\u9970\u5668\uff0c\u540c\u65f6\u6211\u4eec\u4f7f\u7528\u4e86\u00a0<code>@Greeter<\/code>\u00a0\u8bed\u6cd5\u7cd6\uff0c\u6765\u4f7f\u7528\u88c5\u9970\u5668\u3002<\/p>\n<blockquote><p>\u53cb\u60c5\u63d0\u793a\uff1a\u8bfb\u8005\u53ef\u4ee5\u76f4\u63a5\u590d\u5236\u4e0a\u9762\u7684\u4ee3\u7801\uff0c\u5728\u00a0<a title=\"https:\/\/www.typescriptlang.org\/play\/index.html\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fwww.typescriptlang.org%2Fplay%2Findex.html\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript Playground<\/a>\u00a0\u4e2d\u8fd0\u884c\u67e5\u770b\u7ed3\u679c\u3002<\/p><\/blockquote>\n<p>\u6709\u7684\u8bfb\u8005\u53ef\u80fd\u60f3\u95ee\uff0c\u4f8b\u5b50\u4e2d\u603b\u662f\u8f93\u51fa\u00a0<code>Hello Semlinker!<\/code>\u00a0\uff0c\u80fd\u81ea\u5b9a\u4e49\u8f93\u51fa\u7684\u95ee\u5019\u8bed\u4e48 \uff1f\u8fd9\u4e2a\u95ee\u9898\u5f88\u597d\uff0c\u7b54\u6848\u662f\u53ef\u4ee5\u7684\u3002<\/p>\n<p>\u5177\u4f53\u5b9e\u73b0\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">Greeter<\/span>(<span class=\"hljs-params\">greeting: <span class=\"hljs-built_in\">string<\/span><\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (<span class=\"hljs-params\">target: <span class=\"hljs-built_in\">Function<\/span><\/span>) <\/span>{\r\n    target.prototype.greet = <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (): <span class=\"hljs-title\">void<\/span> <\/span>{\r\n      <span class=\"hljs-built_in\">console<\/span>.log(greeting);\r\n    };\r\n  };\r\n}\r\n\r\n<span class=\"hljs-meta\">@Greeter<\/span>(<span class=\"hljs-string\">\"Hello TS!\"<\/span>)\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Greeting<\/span> <\/span>{\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>()<\/span> {\r\n    <span class=\"hljs-comment\">\/\/ \u5185\u90e8\u5b9e\u73b0<\/span>\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> myGreeting = <span class=\"hljs-keyword\">new<\/span> Greeting();\r\n(myGreeting <span class=\"hljs-keyword\">as<\/span> <span class=\"hljs-built_in\">any<\/span>).greet(); <span class=\"hljs-comment\">\/\/ console output: 'Hello TS!';<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-101\">13.4 \u5c5e\u6027\u88c5\u9970\u5668<\/h4>\n<p>\u5c5e\u6027\u88c5\u9970\u5668\u58f0\u660e\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">declare<\/span> <span class=\"hljs-keyword\">type<\/span> PropertyDecorator = <span class=\"hljs-function\">(<span class=\"hljs-params\">target:<span class=\"hljs-built_in\">Object<\/span>, \r\n  propertyKey: <span class=\"hljs-built_in\">string<\/span> | symbol <\/span>) =&gt;<\/span> <span class=\"hljs-built_in\">void<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5c5e\u6027\u88c5\u9970\u5668\u987e\u540d\u601d\u4e49\uff0c\u7528\u6765\u88c5\u9970\u7c7b\u7684\u5c5e\u6027\u3002\u5b83\u63a5\u6536\u4e24\u4e2a\u53c2\u6570\uff1a<\/p>\n<ul>\n<li>target: Object &#8211; \u88ab\u88c5\u9970\u7684\u7c7b<\/li>\n<li>propertyKey: string | symbol &#8211; \u88ab\u88c5\u9970\u7c7b\u7684\u5c5e\u6027\u540d<\/li>\n<\/ul>\n<p>\u8d81\u70ed\u6253\u94c1\uff0c\u9a6c\u4e0a\u6765\u4e2a\u4f8b\u5b50\u70ed\u70ed\u8eab\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">logProperty<\/span>(<span class=\"hljs-params\">target: <span class=\"hljs-built_in\">any<\/span>, key: <span class=\"hljs-built_in\">string<\/span><\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">delete<\/span> target[key];\r\n\r\n  <span class=\"hljs-keyword\">const<\/span> backingField = <span class=\"hljs-string\">\"_\"<\/span> + key;\r\n\r\n  <span class=\"hljs-built_in\">Object<\/span>.defineProperty(target, backingField, {\r\n    <span class=\"hljs-attr\">writable<\/span>: <span class=\"hljs-literal\">true<\/span>,\r\n    <span class=\"hljs-attr\">enumerable<\/span>: <span class=\"hljs-literal\">true<\/span>,\r\n    <span class=\"hljs-attr\">configurable<\/span>: <span class=\"hljs-literal\">true<\/span>\r\n  });\r\n\r\n  <span class=\"hljs-comment\">\/\/ property getter<\/span>\r\n  <span class=\"hljs-keyword\">const<\/span> getter = <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (<span class=\"hljs-params\"><span class=\"hljs-built_in\">this<\/span>: <span class=\"hljs-built_in\">any<\/span><\/span>) <\/span>{\r\n    <span class=\"hljs-keyword\">const<\/span> currVal = <span class=\"hljs-built_in\">this<\/span>[backingField];\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`Get: <span class=\"hljs-subst\">${key}<\/span> =&gt; <span class=\"hljs-subst\">${currVal}<\/span>`<\/span>);\r\n    <span class=\"hljs-keyword\">return<\/span> currVal;\r\n  };\r\n\r\n  <span class=\"hljs-comment\">\/\/ property setter<\/span>\r\n  <span class=\"hljs-keyword\">const<\/span> setter = <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (<span class=\"hljs-params\"><span class=\"hljs-built_in\">this<\/span>: <span class=\"hljs-built_in\">any<\/span>, newVal: <span class=\"hljs-built_in\">any<\/span><\/span>) <\/span>{\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`Set: <span class=\"hljs-subst\">${key}<\/span> =&gt; <span class=\"hljs-subst\">${newVal}<\/span>`<\/span>);\r\n    <span class=\"hljs-built_in\">this<\/span>[backingField] = newVal;\r\n  };\r\n\r\n  <span class=\"hljs-comment\">\/\/ Create new property with getter and setter<\/span>\r\n  <span class=\"hljs-built_in\">Object<\/span>.defineProperty(target, key, {\r\n    <span class=\"hljs-attr\">get<\/span>: getter,\r\n    <span class=\"hljs-attr\">set<\/span>: setter,\r\n    <span class=\"hljs-attr\">enumerable<\/span>: <span class=\"hljs-literal\">true<\/span>,\r\n    <span class=\"hljs-attr\">configurable<\/span>: <span class=\"hljs-literal\">true<\/span>\r\n  });\r\n}\r\n\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Person<\/span> <\/span>{ \r\n  <span class=\"hljs-meta\">@logProperty<\/span>\r\n  <span class=\"hljs-keyword\">public<\/span> name: <span class=\"hljs-built_in\">string<\/span>;\r\n\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\">name : <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> { \r\n    <span class=\"hljs-built_in\">this<\/span>.name = name;\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">const<\/span> p1 = <span class=\"hljs-keyword\">new<\/span> Person(<span class=\"hljs-string\">\"semlinker\"<\/span>);\r\np1.name = <span class=\"hljs-string\">\"kakuqo\"<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a\u4ee3\u7801\u6211\u4eec\u5b9a\u4e49\u4e86\u4e00\u4e2a\u00a0<code>logProperty<\/code>\u00a0\u51fd\u6570\uff0c\u6765\u8ddf\u8e2a\u7528\u6237\u5bf9\u5c5e\u6027\u7684\u64cd\u4f5c\uff0c\u5f53\u4ee3\u7801\u6210\u529f\u8fd0\u884c\u540e\uff0c\u5728\u63a7\u5236\u53f0\u4f1a\u8f93\u51fa\u4ee5\u4e0b\u7ed3\u679c\uff1a<\/p>\n<pre><code class=\"copyable\">Set: name =&gt; semlinker\r\nSet: name =&gt; kakuqo\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-102\">13.5 \u65b9\u6cd5\u88c5\u9970\u5668<\/h4>\n<p>\u65b9\u6cd5\u88c5\u9970\u5668\u58f0\u660e\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">declare<\/span> <span class=\"hljs-keyword\">type<\/span> MethodDecorator = &lt;T&gt;<span class=\"hljs-function\">(<span class=\"hljs-params\">target:<span class=\"hljs-built_in\">Object<\/span>, propertyKey: <span class=\"hljs-built_in\">string<\/span> | symbol, \t \t\r\n  descriptor: TypePropertyDescript&lt;T&gt;<\/span>) =&gt;<\/span> TypedPropertyDescriptor&lt;T&gt; | <span class=\"hljs-built_in\">void<\/span>;\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u65b9\u6cd5\u88c5\u9970\u5668\u987e\u540d\u601d\u4e49\uff0c\u7528\u6765\u88c5\u9970\u7c7b\u7684\u65b9\u6cd5\u3002\u5b83\u63a5\u6536\u4e09\u4e2a\u53c2\u6570\uff1a<\/p>\n<ul>\n<li>target: Object &#8211; \u88ab\u88c5\u9970\u7684\u7c7b<\/li>\n<li>propertyKey: string | symbol &#8211; \u65b9\u6cd5\u540d<\/li>\n<li>descriptor: TypePropertyDescript &#8211; \u5c5e\u6027\u63cf\u8ff0\u7b26<\/li>\n<\/ul>\n<p>\u5e9f\u8bdd\u4e0d\u591a\u8bf4\uff0c\u76f4\u63a5\u4e0a\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">log<\/span>(<span class=\"hljs-params\">target: <span class=\"hljs-built_in\">Object<\/span>, propertyKey: <span class=\"hljs-built_in\">string<\/span>, descriptor: PropertyDescriptor<\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">let<\/span> originalMethod = descriptor.value;\r\n  descriptor.value = <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> (<span class=\"hljs-params\">...args: <span class=\"hljs-built_in\">any<\/span>[]<\/span>) <\/span>{\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"wrapped function: before invoking \"<\/span> + propertyKey);\r\n    <span class=\"hljs-keyword\">let<\/span> result = originalMethod.apply(<span class=\"hljs-built_in\">this<\/span>, args);\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"wrapped function: after invoking \"<\/span> + propertyKey);\r\n    <span class=\"hljs-keyword\">return<\/span> result;\r\n  };\r\n}\r\n\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Task<\/span> <\/span>{\r\n  <span class=\"hljs-meta\">@log<\/span>\r\n  runTask(arg: <span class=\"hljs-built_in\">any<\/span>): <span class=\"hljs-built_in\">any<\/span> {\r\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"runTask invoked, args: \"<\/span> + arg);\r\n    <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-string\">\"finished\"<\/span>;\r\n  }\r\n}\r\n\r\n<span class=\"hljs-keyword\">let<\/span> task = <span class=\"hljs-keyword\">new<\/span> Task();\r\n<span class=\"hljs-keyword\">let<\/span> result = task.runTask(<span class=\"hljs-string\">\"learn ts\"<\/span>);\r\n<span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"result: \"<\/span> + result);\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a\u4ee3\u7801\u6210\u529f\u8fd0\u884c\u540e\uff0c\u63a7\u5236\u53f0\u4f1a\u8f93\u51fa\u4ee5\u4e0b\u7ed3\u679c\uff1a<\/p>\n<pre><code class=\"copyable\">\"wrapped function: before invoking runTask\" \r\n\"runTask invoked, args: learn ts\" \r\n\"wrapped function: after invoking runTask\" \r\n\"result: finished\" \r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4e0b\u9762\u6211\u4eec\u6765\u4ecb\u7ecd\u4e00\u4e0b\u53c2\u6570\u88c5\u9970\u5668\u3002<\/p>\n<h4 data-id=\"heading-103\">13.6 \u53c2\u6570\u88c5\u9970\u5668<\/h4>\n<p>\u53c2\u6570\u88c5\u9970\u5668\u58f0\u660e\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-keyword\">declare<\/span> <span class=\"hljs-keyword\">type<\/span> ParameterDecorator = <span class=\"hljs-function\">(<span class=\"hljs-params\">target: <span class=\"hljs-built_in\">Object<\/span>, propertyKey: <span class=\"hljs-built_in\">string<\/span> | symbol, \r\n  parameterIndex: <span class=\"hljs-built_in\">number<\/span> <\/span>) =&gt;<\/span> <span class=\"hljs-built_in\">void<\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u53c2\u6570\u88c5\u9970\u5668\u987e\u540d\u601d\u4e49\uff0c\u662f\u7528\u6765\u88c5\u9970\u51fd\u6570\u53c2\u6570\uff0c\u5b83\u63a5\u6536\u4e09\u4e2a\u53c2\u6570\uff1a<\/p>\n<ul>\n<li>target: Object &#8211; \u88ab\u88c5\u9970\u7684\u7c7b<\/li>\n<li>propertyKey: string | symbol &#8211; \u65b9\u6cd5\u540d<\/li>\n<li>parameterIndex: number &#8211; \u65b9\u6cd5\u4e2d\u53c2\u6570\u7684\u7d22\u5f15\u503c<\/li>\n<\/ul>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">Log<\/span>(<span class=\"hljs-params\">target: <span class=\"hljs-built_in\">Function<\/span>, key: <span class=\"hljs-built_in\">string<\/span>, parameterIndex: <span class=\"hljs-built_in\">number<\/span><\/span>) <\/span>{\r\n  <span class=\"hljs-keyword\">let<\/span> functionLogged = key || target.prototype.constructor.name;\r\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`The parameter in position <span class=\"hljs-subst\">${parameterIndex}<\/span> at <span class=\"hljs-subst\">${functionLogged}<\/span> has\r\n\tbeen decorated`<\/span>);\r\n}\r\n\r\n<span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Greeter<\/span> <\/span>{\r\n  <span class=\"hljs-attr\">greeting<\/span>: <span class=\"hljs-built_in\">string<\/span>;\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\"><span class=\"hljs-meta\">@Log<\/span> phrase: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> {\r\n\t<span class=\"hljs-built_in\">this<\/span>.greeting = phrase; \r\n  }\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ee5\u4e0a\u4ee3\u7801\u6210\u529f\u8fd0\u884c\u540e\uff0c\u63a7\u5236\u53f0\u4f1a\u8f93\u51fa\u4ee5\u4e0b\u7ed3\u679c\uff1a<\/p>\n<pre><code class=\"copyable\">\"The parameter in position 0 at Greeter has been decorated\" \r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h3 data-id=\"heading-104\">\u5341\u56db\u3001TypeScript 4.0 \u65b0\u7279\u6027<\/h3>\n<p>TypeScript 4.0 \u5e26\u6765\u4e86\u5f88\u591a\u65b0\u7684\u7279\u6027\uff0c\u8fd9\u91cc\u6211\u4eec\u53ea\u7b80\u5355\u4ecb\u7ecd\u5176\u4e2d\u7684\u4e24\u4e2a\u65b0\u7279\u6027\u3002<\/p>\n<h4 data-id=\"heading-105\">14.1 \u6784\u9020\u51fd\u6570\u7684\u7c7b\u5c5e\u6027\u63a8\u65ad<\/h4>\n<p>\u5f53\u00a0<code>noImplicitAny<\/code>\u00a0\u914d\u7f6e\u5c5e\u6027\u88ab\u542f\u7528\u4e4b\u540e\uff0cTypeScript 4.0 \u5c31\u53ef\u4ee5\u4f7f\u7528\u63a7\u5236\u6d41\u5206\u6790\u6765\u786e\u8ba4\u7c7b\u4e2d\u7684\u5c5e\u6027\u7c7b\u578b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Person<\/span> <\/span>{\r\n  fullName; <span class=\"hljs-comment\">\/\/ (property) Person.fullName: string<\/span>\r\n  firstName; <span class=\"hljs-comment\">\/\/ (property) Person.firstName: string<\/span>\r\n  lastName; <span class=\"hljs-comment\">\/\/ (property) Person.lastName: string<\/span>\r\n\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\">fullName: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> {\r\n    <span class=\"hljs-built_in\">this<\/span>.fullName = fullName;\r\n    <span class=\"hljs-built_in\">this<\/span>.firstName = fullName.split(<span class=\"hljs-string\">\" \"<\/span>)[<span class=\"hljs-number\">0<\/span>];\r\n    <span class=\"hljs-built_in\">this<\/span>.lastName =   fullName.split(<span class=\"hljs-string\">\" \"<\/span>)[<span class=\"hljs-number\">1<\/span>];\r\n  }  \r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u7136\u800c\u5bf9\u4e8e\u4ee5\u4e0a\u7684\u4ee3\u7801\uff0c\u5982\u679c\u5728 TypeScript 4.0 \u4ee5\u524d\u7684\u7248\u672c\uff0c\u6bd4\u5982\u5728 3.9.2 \u7248\u672c\u4e0b\uff0c\u7f16\u8bd1\u5668\u4f1a\u63d0\u793a\u4ee5\u4e0b\u9519\u8bef\u4fe1\u606f\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Person<\/span> <\/span>{\r\n  <span class=\"hljs-comment\">\/\/ Member 'fullName' implicitly has an 'any' type.(7008)<\/span>\r\n  fullName; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n  firstName; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n  lastName; <span class=\"hljs-comment\">\/\/ Error<\/span>\r\n\r\n  <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\">fullName: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> {\r\n    <span class=\"hljs-built_in\">this<\/span>.fullName = fullName;\r\n    <span class=\"hljs-built_in\">this<\/span>.firstName = fullName.split(<span class=\"hljs-string\">\" \"<\/span>)[<span class=\"hljs-number\">0<\/span>];\r\n    <span class=\"hljs-built_in\">this<\/span>.lastName =   fullName.split(<span class=\"hljs-string\">\" \"<\/span>)[<span class=\"hljs-number\">1<\/span>];\r\n  }  \r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4ece\u6784\u9020\u51fd\u6570\u63a8\u65ad\u7c7b\u5c5e\u6027\u7684\u7c7b\u578b\uff0c\u8be5\u7279\u6027\u7ed9\u6211\u4eec\u5e26\u6765\u4e86\u4fbf\u5229\u3002\u4f46\u5728\u4f7f\u7528\u8fc7\u7a0b\u4e2d\uff0c\u5982\u679c\u6211\u4eec\u6ca1\u6cd5\u4fdd\u8bc1\u5bf9\u6210\u5458\u5c5e\u6027\u90fd\u8fdb\u884c\u8d4b\u503c\uff0c\u90a3\u4e48\u8be5\u5c5e\u6027\u53ef\u80fd\u4f1a\u88ab\u8ba4\u4e3a\u662f\u00a0<code>undefined<\/code>\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-class\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Person<\/span> <\/span>{\r\n   fullName;  <span class=\"hljs-comment\">\/\/ (property) Person.fullName: string<\/span>\r\n   firstName; <span class=\"hljs-comment\">\/\/ (property) Person.firstName: string | undefined<\/span>\r\n   lastName; <span class=\"hljs-comment\">\/\/ (property) Person.lastName: string | undefined<\/span>\r\n\r\n   <span class=\"hljs-function\"><span class=\"hljs-title\">constructor<\/span>(<span class=\"hljs-params\">fullName: <span class=\"hljs-built_in\">string<\/span><\/span>)<\/span> {\r\n     <span class=\"hljs-built_in\">this<\/span>.fullName = fullName;\r\n     <span class=\"hljs-keyword\">if<\/span>(<span class=\"hljs-built_in\">Math<\/span>.random()){\r\n       <span class=\"hljs-built_in\">this<\/span>.firstName = fullName.split(<span class=\"hljs-string\">\" \"<\/span>)[<span class=\"hljs-number\">0<\/span>];\r\n       <span class=\"hljs-built_in\">this<\/span>.lastName =   fullName.split(<span class=\"hljs-string\">\" \"<\/span>)[<span class=\"hljs-number\">1<\/span>];\r\n     }\r\n   }  \r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h4 data-id=\"heading-106\">14.2 \u6807\u8bb0\u7684\u5143\u7ec4\u5143\u7d20<\/h4>\n<p>\u5728\u4ee5\u4e0b\u7684\u793a\u4f8b\u4e2d\uff0c\u6211\u4eec\u4f7f\u7528\u5143\u7ec4\u7c7b\u578b\u6765\u58f0\u660e\u5269\u4f59\u53c2\u6570\u7684\u7c7b\u578b\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">addPerson<\/span>(<span class=\"hljs-params\">...args: [<span class=\"hljs-built_in\">string<\/span>, <span class=\"hljs-built_in\">number<\/span>]<\/span>): <span class=\"hljs-title\">void<\/span> <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`Person info: name: <span class=\"hljs-subst\">${args[<span class=\"hljs-number\">0<\/span>]}<\/span>, age: <span class=\"hljs-subst\">${args[<span class=\"hljs-number\">1<\/span>]}<\/span>`<\/span>)\r\n}\r\n\r\naddPerson(<span class=\"hljs-string\">\"lolo\"<\/span>, <span class=\"hljs-number\">5<\/span>); <span class=\"hljs-comment\">\/\/ Person info: name: lolo, age: 5 <\/span>\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u5176\u5b9e\uff0c\u5bf9\u4e8e\u4e0a\u9762\u7684\u00a0<code>addPerson<\/code>\u00a0\u51fd\u6570\uff0c\u6211\u4eec\u4e5f\u53ef\u4ee5\u8fd9\u6837\u5b9e\u73b0\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">addPerson<\/span>(<span class=\"hljs-params\">name: <span class=\"hljs-built_in\">string<\/span>, age: <span class=\"hljs-built_in\">number<\/span><\/span>) <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`Person info: name: <span class=\"hljs-subst\">${name}<\/span>, age: <span class=\"hljs-subst\">${age}<\/span>`<\/span>)\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u8fd9\u4e24\u79cd\u65b9\u5f0f\u770b\u8d77\u6765\u6ca1\u6709\u591a\u5927\u7684\u533a\u522b\uff0c\u4f46\u5bf9\u4e8e\u7b2c\u4e00\u79cd\u65b9\u5f0f\uff0c\u6211\u4eec\u6ca1\u6cd5\u8bbe\u7f6e\u7b2c\u4e00\u4e2a\u53c2\u6570\u548c\u7b2c\u4e8c\u4e2a\u53c2\u6570\u7684\u540d\u79f0\u3002\u867d\u7136\u8fd9\u6837\u5bf9\u7c7b\u578b\u68c0\u67e5\u6ca1\u6709\u5f71\u54cd\uff0c\u4f46\u5728\u5143\u7ec4\u4f4d\u7f6e\u4e0a\u7f3a\u5c11\u6807\u7b7e\uff0c\u4f1a\u4f7f\u5f97\u5b83\u4eec\u96be\u4e8e\u4f7f\u7528\u3002\u4e3a\u4e86\u63d0\u9ad8\u5f00\u53d1\u8005\u4f7f\u7528\u5143\u7ec4\u7684\u4f53\u9a8c\uff0cTypeScript 4.0 \u652f\u6301\u4e3a\u5143\u7ec4\u7c7b\u578b\u8bbe\u7f6e\u6807\u7b7e\uff1a<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">addPerson<\/span>(<span class=\"hljs-params\">...args: [name: <span class=\"hljs-built_in\">string<\/span>, age: <span class=\"hljs-built_in\">number<\/span>]<\/span>): <span class=\"hljs-title\">void<\/span> <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`Person info: name: <span class=\"hljs-subst\">${args[<span class=\"hljs-number\">0<\/span>]}<\/span>, age: <span class=\"hljs-subst\">${args[<span class=\"hljs-number\">1<\/span>]}<\/span>`<\/span>);\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<p>\u4e4b\u540e\uff0c\u5f53\u6211\u4eec\u4f7f\u7528\u00a0<code>addPerson<\/code>\u00a0\u65b9\u6cd5\u65f6\uff0cTypeScript \u7684\u667a\u80fd\u63d0\u793a\u5c31\u4f1a\u53d8\u5f97\u66f4\u52a0\u53cb\u597d\u3002<\/p>\n<pre><code class=\"hljs language-typescript copyable\" lang=\"typescript\"><span class=\"hljs-comment\">\/\/ \u672a\u4f7f\u7528\u6807\u7b7e\u7684\u667a\u80fd\u63d0\u793a<\/span>\r\n<span class=\"hljs-comment\">\/\/ addPerson(args_0: string, args_1: number): void<\/span>\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">addPerson<\/span>(<span class=\"hljs-params\">...args: [<span class=\"hljs-built_in\">string<\/span>, <span class=\"hljs-built_in\">number<\/span>]<\/span>): <span class=\"hljs-title\">void<\/span> <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`Person info: name: <span class=\"hljs-subst\">${args[<span class=\"hljs-number\">0<\/span>]}<\/span>, age: <span class=\"hljs-subst\">${args[<span class=\"hljs-number\">1<\/span>]}<\/span>`<\/span>)\r\n} \r\n\r\n<span class=\"hljs-comment\">\/\/ \u5df2\u4f7f\u7528\u6807\u7b7e\u7684\u667a\u80fd\u63d0\u793a<\/span>\r\n<span class=\"hljs-comment\">\/\/ addPerson(name: string, age: number): void<\/span>\r\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">addPerson<\/span>(<span class=\"hljs-params\">...args: [name: <span class=\"hljs-built_in\">string<\/span>, age: <span class=\"hljs-built_in\">number<\/span>]<\/span>): <span class=\"hljs-title\">void<\/span> <\/span>{\r\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`Person info: name: <span class=\"hljs-subst\">${args[<span class=\"hljs-number\">0<\/span>]}<\/span>, age: <span class=\"hljs-subst\">${args[<span class=\"hljs-number\">1<\/span>]}<\/span>`<\/span>);\r\n} \r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h3 data-id=\"heading-107\">\u5341\u4e94\u3001\u7f16\u8bd1\u4e0a\u4e0b\u6587<\/h3>\n<h4 data-id=\"heading-108\">15.1 tsconfig.json \u7684\u4f5c\u7528<\/h4>\n<ul>\n<li>\u7528\u4e8e\u6807\u8bc6 TypeScript \u9879\u76ee\u7684\u6839\u8def\u5f84\uff1b<\/li>\n<li>\u7528\u4e8e\u914d\u7f6e TypeScript \u7f16\u8bd1\u5668\uff1b<\/li>\n<li>\u7528\u4e8e\u6307\u5b9a\u7f16\u8bd1\u7684\u6587\u4ef6\u3002<\/li>\n<\/ul>\n<h4 data-id=\"heading-109\">15.2 tsconfig.json \u91cd\u8981\u5b57\u6bb5<\/h4>\n<ul>\n<li>files &#8211; \u8bbe\u7f6e\u8981\u7f16\u8bd1\u7684\u6587\u4ef6\u7684\u540d\u79f0\uff1b<\/li>\n<li>include &#8211; \u8bbe\u7f6e\u9700\u8981\u8fdb\u884c\u7f16\u8bd1\u7684\u6587\u4ef6\uff0c\u652f\u6301\u8def\u5f84\u6a21\u5f0f\u5339\u914d\uff1b<\/li>\n<li>exclude &#8211; \u8bbe\u7f6e\u65e0\u9700\u8fdb\u884c\u7f16\u8bd1\u7684\u6587\u4ef6\uff0c\u652f\u6301\u8def\u5f84\u6a21\u5f0f\u5339\u914d\uff1b<\/li>\n<li>compilerOptions &#8211; \u8bbe\u7f6e\u4e0e\u7f16\u8bd1\u6d41\u7a0b\u76f8\u5173\u7684\u9009\u9879\u3002<\/li>\n<\/ul>\n<h4 data-id=\"heading-110\">15.3 compilerOptions \u9009\u9879<\/h4>\n<p>compilerOptions \u652f\u6301\u5f88\u591a\u9009\u9879\uff0c\u5e38\u89c1\u7684\u6709\u00a0<code>baseUrl<\/code>\u3001\u00a0<code>target<\/code>\u3001<code>baseUrl<\/code>\u3001\u00a0<code>moduleResolution<\/code>\u00a0\u548c\u00a0<code>lib<\/code>\u00a0\u7b49\u3002<\/p>\n<p>compilerOptions \u6bcf\u4e2a\u9009\u9879\u7684\u8be6\u7ec6\u8bf4\u660e\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"hljs language-json copyable\" lang=\"json\">{\r\n  <span class=\"hljs-attr\">\"compilerOptions\"<\/span>: {\r\n\r\n    <span class=\"hljs-comment\">\/* \u57fa\u672c\u9009\u9879 *\/<\/span>\r\n    <span class=\"hljs-attr\">\"target\"<\/span>: <span class=\"hljs-string\">\"es5\"<\/span>,                       <span class=\"hljs-comment\">\/\/ \u6307\u5b9a ECMAScript \u76ee\u6807\u7248\u672c: 'ES3' (default), 'ES5', 'ES6'\/'ES2015', 'ES2016', 'ES2017', or 'ESNEXT'<\/span>\r\n    <span class=\"hljs-attr\">\"module\"<\/span>: <span class=\"hljs-string\">\"commonjs\"<\/span>,                  <span class=\"hljs-comment\">\/\/ \u6307\u5b9a\u4f7f\u7528\u6a21\u5757: 'commonjs', 'amd', 'system', 'umd' or 'es2015'<\/span>\r\n    <span class=\"hljs-attr\">\"lib\"<\/span>: [],                             <span class=\"hljs-comment\">\/\/ \u6307\u5b9a\u8981\u5305\u542b\u5728\u7f16\u8bd1\u4e2d\u7684\u5e93\u6587\u4ef6<\/span>\r\n    <span class=\"hljs-attr\">\"allowJs\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                       <span class=\"hljs-comment\">\/\/ \u5141\u8bb8\u7f16\u8bd1 javascript \u6587\u4ef6<\/span>\r\n    <span class=\"hljs-attr\">\"checkJs\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                       <span class=\"hljs-comment\">\/\/ \u62a5\u544a javascript \u6587\u4ef6\u4e2d\u7684\u9519\u8bef<\/span>\r\n    <span class=\"hljs-attr\">\"jsx\"<\/span>: <span class=\"hljs-string\">\"preserve\"<\/span>,                     <span class=\"hljs-comment\">\/\/ \u6307\u5b9a jsx \u4ee3\u7801\u7684\u751f\u6210: 'preserve', 'react-native', or 'react'<\/span>\r\n    <span class=\"hljs-attr\">\"declaration\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                   <span class=\"hljs-comment\">\/\/ \u751f\u6210\u76f8\u5e94\u7684 '.d.ts' \u6587\u4ef6<\/span>\r\n    <span class=\"hljs-attr\">\"sourceMap\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                     <span class=\"hljs-comment\">\/\/ \u751f\u6210\u76f8\u5e94\u7684 '.map' \u6587\u4ef6<\/span>\r\n    <span class=\"hljs-attr\">\"outFile\"<\/span>: <span class=\"hljs-string\">\".\/\"<\/span>,                       <span class=\"hljs-comment\">\/\/ \u5c06\u8f93\u51fa\u6587\u4ef6\u5408\u5e76\u4e3a\u4e00\u4e2a\u6587\u4ef6<\/span>\r\n    <span class=\"hljs-attr\">\"outDir\"<\/span>: <span class=\"hljs-string\">\".\/\"<\/span>,                        <span class=\"hljs-comment\">\/\/ \u6307\u5b9a\u8f93\u51fa\u76ee\u5f55<\/span>\r\n    <span class=\"hljs-attr\">\"rootDir\"<\/span>: <span class=\"hljs-string\">\".\/\"<\/span>,                       <span class=\"hljs-comment\">\/\/ \u7528\u6765\u63a7\u5236\u8f93\u51fa\u76ee\u5f55\u7ed3\u6784 --outDir.<\/span>\r\n    <span class=\"hljs-attr\">\"removeComments\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                <span class=\"hljs-comment\">\/\/ \u5220\u9664\u7f16\u8bd1\u540e\u7684\u6240\u6709\u7684\u6ce8\u91ca<\/span>\r\n    <span class=\"hljs-attr\">\"noEmit\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                        <span class=\"hljs-comment\">\/\/ \u4e0d\u751f\u6210\u8f93\u51fa\u6587\u4ef6<\/span>\r\n    <span class=\"hljs-attr\">\"importHelpers\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                 <span class=\"hljs-comment\">\/\/ \u4ece tslib \u5bfc\u5165\u8f85\u52a9\u5de5\u5177\u51fd\u6570<\/span>\r\n    <span class=\"hljs-attr\">\"isolatedModules\"<\/span>: <span class=\"hljs-literal\">true<\/span>,               <span class=\"hljs-comment\">\/\/ \u5c06\u6bcf\u4e2a\u6587\u4ef6\u505a\u4e3a\u5355\u72ec\u7684\u6a21\u5757 \uff08\u4e0e 'ts.transpileModule' \u7c7b\u4f3c\uff09.<\/span>\r\n\r\n    <span class=\"hljs-comment\">\/* \u4e25\u683c\u7684\u7c7b\u578b\u68c0\u67e5\u9009\u9879 *\/<\/span>\r\n    <span class=\"hljs-attr\">\"strict\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                        <span class=\"hljs-comment\">\/\/ \u542f\u7528\u6240\u6709\u4e25\u683c\u7c7b\u578b\u68c0\u67e5\u9009\u9879<\/span>\r\n    <span class=\"hljs-attr\">\"noImplicitAny\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                 <span class=\"hljs-comment\">\/\/ \u5728\u8868\u8fbe\u5f0f\u548c\u58f0\u660e\u4e0a\u6709\u9690\u542b\u7684 any\u7c7b\u578b\u65f6\u62a5\u9519<\/span>\r\n    <span class=\"hljs-attr\">\"strictNullChecks\"<\/span>: <span class=\"hljs-literal\">true<\/span>,              <span class=\"hljs-comment\">\/\/ \u542f\u7528\u4e25\u683c\u7684 null \u68c0\u67e5<\/span>\r\n    <span class=\"hljs-attr\">\"noImplicitThis\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                <span class=\"hljs-comment\">\/\/ \u5f53 this \u8868\u8fbe\u5f0f\u503c\u4e3a any \u7c7b\u578b\u7684\u65f6\u5019\uff0c\u751f\u6210\u4e00\u4e2a\u9519\u8bef<\/span>\r\n    <span class=\"hljs-attr\">\"alwaysStrict\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                  <span class=\"hljs-comment\">\/\/ \u4ee5\u4e25\u683c\u6a21\u5f0f\u68c0\u67e5\u6bcf\u4e2a\u6a21\u5757\uff0c\u5e76\u5728\u6bcf\u4e2a\u6587\u4ef6\u91cc\u52a0\u5165 'use strict'<\/span>\r\n\r\n    <span class=\"hljs-comment\">\/* \u989d\u5916\u7684\u68c0\u67e5 *\/<\/span>\r\n    <span class=\"hljs-attr\">\"noUnusedLocals\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                <span class=\"hljs-comment\">\/\/ \u6709\u672a\u4f7f\u7528\u7684\u53d8\u91cf\u65f6\uff0c\u629b\u51fa\u9519\u8bef<\/span>\r\n    <span class=\"hljs-attr\">\"noUnusedParameters\"<\/span>: <span class=\"hljs-literal\">true<\/span>,            <span class=\"hljs-comment\">\/\/ \u6709\u672a\u4f7f\u7528\u7684\u53c2\u6570\u65f6\uff0c\u629b\u51fa\u9519\u8bef<\/span>\r\n    <span class=\"hljs-attr\">\"noImplicitReturns\"<\/span>: <span class=\"hljs-literal\">true<\/span>,             <span class=\"hljs-comment\">\/\/ \u5e76\u4e0d\u662f\u6240\u6709\u51fd\u6570\u91cc\u7684\u4ee3\u7801\u90fd\u6709\u8fd4\u56de\u503c\u65f6\uff0c\u629b\u51fa\u9519\u8bef<\/span>\r\n    <span class=\"hljs-attr\">\"noFallthroughCasesInSwitch\"<\/span>: <span class=\"hljs-literal\">true<\/span>,    <span class=\"hljs-comment\">\/\/ \u62a5\u544a switch \u8bed\u53e5\u7684 fallthrough \u9519\u8bef\u3002\uff08\u5373\uff0c\u4e0d\u5141\u8bb8 switch \u7684 case \u8bed\u53e5\u8d2f\u7a7f\uff09<\/span>\r\n\r\n    <span class=\"hljs-comment\">\/* \u6a21\u5757\u89e3\u6790\u9009\u9879 *\/<\/span>\r\n    <span class=\"hljs-attr\">\"moduleResolution\"<\/span>: <span class=\"hljs-string\">\"node\"<\/span>,            <span class=\"hljs-comment\">\/\/ \u9009\u62e9\u6a21\u5757\u89e3\u6790\u7b56\u7565\uff1a 'node' (Node.js) or 'classic' (TypeScript pre-1.6)<\/span>\r\n    <span class=\"hljs-attr\">\"baseUrl\"<\/span>: <span class=\"hljs-string\">\".\/\"<\/span>,                       <span class=\"hljs-comment\">\/\/ \u7528\u4e8e\u89e3\u6790\u975e\u76f8\u5bf9\u6a21\u5757\u540d\u79f0\u7684\u57fa\u76ee\u5f55<\/span>\r\n    <span class=\"hljs-attr\">\"paths\"<\/span>: {},                           <span class=\"hljs-comment\">\/\/ \u6a21\u5757\u540d\u5230\u57fa\u4e8e baseUrl \u7684\u8def\u5f84\u6620\u5c04\u7684\u5217\u8868<\/span>\r\n    <span class=\"hljs-attr\">\"rootDirs\"<\/span>: [],                        <span class=\"hljs-comment\">\/\/ \u6839\u6587\u4ef6\u5939\u5217\u8868\uff0c\u5176\u7ec4\u5408\u5185\u5bb9\u8868\u793a\u9879\u76ee\u8fd0\u884c\u65f6\u7684\u7ed3\u6784\u5185\u5bb9<\/span>\r\n    <span class=\"hljs-attr\">\"typeRoots\"<\/span>: [],                       <span class=\"hljs-comment\">\/\/ \u5305\u542b\u7c7b\u578b\u58f0\u660e\u7684\u6587\u4ef6\u5217\u8868<\/span>\r\n    <span class=\"hljs-attr\">\"types\"<\/span>: [],                           <span class=\"hljs-comment\">\/\/ \u9700\u8981\u5305\u542b\u7684\u7c7b\u578b\u58f0\u660e\u6587\u4ef6\u540d\u5217\u8868<\/span>\r\n    <span class=\"hljs-attr\">\"allowSyntheticDefaultImports\"<\/span>: <span class=\"hljs-literal\">true<\/span>,  <span class=\"hljs-comment\">\/\/ \u5141\u8bb8\u4ece\u6ca1\u6709\u8bbe\u7f6e\u9ed8\u8ba4\u5bfc\u51fa\u7684\u6a21\u5757\u4e2d\u9ed8\u8ba4\u5bfc\u5165\u3002<\/span>\r\n\r\n    <span class=\"hljs-comment\">\/* Source Map Options *\/<\/span>\r\n    <span class=\"hljs-attr\">\"sourceRoot\"<\/span>: <span class=\"hljs-string\">\".\/\"<\/span>,                    <span class=\"hljs-comment\">\/\/ \u6307\u5b9a\u8c03\u8bd5\u5668\u5e94\u8be5\u627e\u5230 TypeScript \u6587\u4ef6\u800c\u4e0d\u662f\u6e90\u6587\u4ef6\u7684\u4f4d\u7f6e<\/span>\r\n    <span class=\"hljs-attr\">\"mapRoot\"<\/span>: <span class=\"hljs-string\">\".\/\"<\/span>,                       <span class=\"hljs-comment\">\/\/ \u6307\u5b9a\u8c03\u8bd5\u5668\u5e94\u8be5\u627e\u5230\u6620\u5c04\u6587\u4ef6\u800c\u4e0d\u662f\u751f\u6210\u6587\u4ef6\u7684\u4f4d\u7f6e<\/span>\r\n    <span class=\"hljs-attr\">\"inlineSourceMap\"<\/span>: <span class=\"hljs-literal\">true<\/span>,               <span class=\"hljs-comment\">\/\/ \u751f\u6210\u5355\u4e2a soucemaps \u6587\u4ef6\uff0c\u800c\u4e0d\u662f\u5c06 sourcemaps \u751f\u6210\u4e0d\u540c\u7684\u6587\u4ef6<\/span>\r\n    <span class=\"hljs-attr\">\"inlineSources\"<\/span>: <span class=\"hljs-literal\">true<\/span>,                 <span class=\"hljs-comment\">\/\/ \u5c06\u4ee3\u7801\u4e0e sourcemaps \u751f\u6210\u5230\u4e00\u4e2a\u6587\u4ef6\u4e2d\uff0c\u8981\u6c42\u540c\u65f6\u8bbe\u7f6e\u4e86 --inlineSourceMap \u6216 --sourceMap \u5c5e\u6027<\/span>\r\n\r\n    <span class=\"hljs-comment\">\/* \u5176\u4ed6\u9009\u9879 *\/<\/span>\r\n    <span class=\"hljs-attr\">\"experimentalDecorators\"<\/span>: <span class=\"hljs-literal\">true<\/span>,        <span class=\"hljs-comment\">\/\/ \u542f\u7528\u88c5\u9970\u5668<\/span>\r\n    <span class=\"hljs-attr\">\"emitDecoratorMetadata\"<\/span>: <span class=\"hljs-literal\">true<\/span>          <span class=\"hljs-comment\">\/\/ \u4e3a\u88c5\u9970\u5668\u63d0\u4f9b\u5143\u6570\u636e\u7684\u652f\u6301<\/span>\r\n  }\r\n}\r\n<span class=\"copy-code-btn\">\u590d\u5236\u4ee3\u7801<\/span><\/code><\/pre>\n<h3 data-id=\"heading-111\">\u5341\u516d\u3001TypeScript \u5f00\u53d1\u8f85\u52a9\u5de5\u5177<\/h3>\n<h4 data-id=\"heading-112\">16.1\u00a0<a title=\"https:\/\/www.typescriptlang.org\/play\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fwww.typescriptlang.org%2Fplay%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript Playground<\/a><\/h4>\n<blockquote><p>\u7b80\u4ecb\uff1aTypeScript \u5b98\u65b9\u63d0\u4f9b\u7684\u5728\u7ebf TypeScript \u8fd0\u884c\u73af\u5883\uff0c\u5229\u7528\u5b83\u4f60\u53ef\u4ee5\u65b9\u4fbf\u5730\u5b66\u4e60 TypeScript \u76f8\u5173\u77e5\u8bc6\u4e0e\u4e0d\u540c\u7248\u672c\u7684\u529f\u80fd\u7279\u6027\u3002<\/p>\n<p>\u5728\u7ebf\u5730\u5740\uff1a<a title=\"https:\/\/www.typescriptlang.org\/play\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fwww.typescriptlang.org%2Fplay%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">www.typescriptlang.org\/play\/<\/a><\/p><\/blockquote>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p1-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/3f0f847192f5476fbab2d36e2c28df5f~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\u9664\u4e86 TypeScript \u5b98\u65b9\u7684 Playground \u4e4b\u5916\uff0c\u4f60\u8fd8\u53ef\u4ee5\u9009\u62e9\u5176\u4ed6\u7684 Playground\uff0c\u6bd4\u5982\u00a0<a title=\"https:\/\/codepen.io\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fcodepen.io%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">codepen.io<\/a>\u3001<a title=\"https:\/\/stackblitz.com\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fstackblitz.com%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">stackblitz<\/a>\u00a0\u6216\u00a0<a title=\"https:\/\/jsbin.com\/?js\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fjsbin.com%2F%3Fjs\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">jsbin.com<\/a>\u00a0\u7b49\u3002<\/p>\n<h4 data-id=\"heading-113\">16.2\u00a0<a title=\"https:\/\/tsuml-demo.firebaseapp.com\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Ftsuml-demo.firebaseapp.com%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript UML Playground<\/a><\/h4>\n<blockquote><p>\u7b80\u4ecb\uff1a\u4e00\u6b3e\u5728\u7ebf TypeScript UML \u5de5\u5177\uff0c\u5229\u7528\u5b83\u4f60\u53ef\u4ee5\u4e3a\u6307\u5b9a\u7684 TypeScript \u4ee3\u7801\u751f\u6210 UML \u7c7b\u56fe\u3002<\/p>\n<p>\u5728\u7ebf\u5730\u5740\uff1a<a title=\"https:\/\/tsuml-demo.firebaseapp.com\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Ftsuml-demo.firebaseapp.com%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">tsuml-demo.firebaseapp.com\/<\/a><\/p><\/blockquote>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p3-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/ba1007ed5c55434a9ef12a3792c2ab80~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<h4 data-id=\"heading-114\">16.3\u00a0<a title=\"http:\/\/www.jsontots.com\/\" href=\"https:\/\/link.juejin.cn\/?target=http%3A%2F%2Fwww.jsontots.com%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">JSON TO TS<\/a><\/h4>\n<blockquote><p>\u7b80\u4ecb\uff1a\u4e00\u6b3e TypeScript \u5728\u7ebf\u5de5\u5177\uff0c\u5229\u7528\u5b83\u4f60\u53ef\u4ee5\u4e3a\u6307\u5b9a\u7684 JSON \u6570\u636e\u751f\u6210\u5bf9\u5e94\u7684 TypeScript \u63a5\u53e3\u5b9a\u4e49\u3002<\/p>\n<p>\u5728\u7ebf\u5730\u5740\uff1a<a title=\"http:\/\/www.jsontots.com\/\" href=\"https:\/\/link.juejin.cn\/?target=http%3A%2F%2Fwww.jsontots.com%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">www.jsontots.com\/<\/a><\/p><\/blockquote>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p1-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/037bbc7a84e145ad8ac13e1e8e49b115~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\u9664\u4e86\u4f7f\u7528\u00a0<a title=\"http:\/\/www.jsontots.com\/\" href=\"https:\/\/link.juejin.cn\/?target=http%3A%2F%2Fwww.jsontots.com%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">jsontots<\/a>\u00a0\u5728\u7ebf\u5de5\u5177\u4e4b\u5916\uff0c\u5bf9\u4e8e\u4f7f\u7528 VSCode IDE \u7684\u5c0f\u4f19\u4eec\u8fd8\u53ef\u4ee5\u5b89\u88c5\u00a0<a title=\"https:\/\/marketplace.visualstudio.com\/items?itemName=MariusAlchimavicius.json-to-ts\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fmarketplace.visualstudio.com%2Fitems%3FitemName%3DMariusAlchimavicius.json-to-ts\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">JSON to TS<\/a>\u00a0\u6269\u5c55\u6765\u5feb\u901f\u5b8c\u6210\u00a0<strong>JSON to TS<\/strong>\u00a0\u7684\u8f6c\u6362\u5de5\u4f5c\u3002<\/p>\n<h4 data-id=\"heading-115\">16.4\u00a0<a title=\"https:\/\/github.com\/SweetIQ\/schemats\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fgithub.com%2FSweetIQ%2Fschemats\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">Schemats<\/a><\/h4>\n<blockquote><p>\u7b80\u4ecb\uff1a\u5229\u7528 Schemats\uff0c\u4f60\u53ef\u4ee5\u57fa\u4e8e\uff08Postgres\uff0cMySQL\uff09SQL \u6570\u636e\u5e93\u4e2d\u7684 schema \u81ea\u52a8\u751f\u6210 TypeScript \u63a5\u53e3\u5b9a\u4e49\u3002<\/p>\n<p>\u5728\u7ebf\u5730\u5740\uff1a<a title=\"https:\/\/github.com\/SweetIQ\/schemats\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fgithub.com%2FSweetIQ%2Fschemats\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">github.com\/SweetIQ\/sch\u2026<\/a><\/p><\/blockquote>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p9-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/20e5b6e73c5a48bd9118b5c4f61e6c43~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<h4 data-id=\"heading-116\">16.5\u00a0<a title=\"https:\/\/ts-ast-viewer.com\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fts-ast-viewer.com%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript AST Viewer<\/a><\/h4>\n<blockquote><p>\u7b80\u4ecb\uff1a\u4e00\u6b3e TypeScript AST \u5728\u7ebf\u5de5\u5177\uff0c\u5229\u7528\u5b83\u4f60\u53ef\u4ee5\u67e5\u770b\u6307\u5b9a TypeScript \u4ee3\u7801\u5bf9\u5e94\u7684 AST\uff08Abstract Syntax Tree\uff09\u62bd\u8c61\u8bed\u6cd5\u6811\u3002<\/p>\n<p>\u5728\u7ebf\u5730\u5740\uff1a<a title=\"https:\/\/ts-ast-viewer.com\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fts-ast-viewer.com%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">ts-ast-viewer.com\/<\/a><\/p><\/blockquote>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p1-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/baf0f0d1dd9c488893d0cc3c3eaa45bd~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\u5bf9\u4e8e\u4e86\u89e3\u8fc7 AST \u7684\u5c0f\u4f19\u4f34\u6765\u8bf4\uff0c\u5bf9\u00a0<a title=\"https:\/\/astexplorer.net\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fastexplorer.net%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">astexplorer<\/a>\u00a0\u8fd9\u6b3e\u5728\u7ebf\u5de5\u5177\u5e94\u8be5\u4e0d\u4f1a\u964c\u751f\u3002\u8be5\u5de5\u5177\u9664\u4e86\u652f\u6301 JavaScript \u4e4b\u5916\uff0c\u8fd8\u652f\u6301 CSS\u3001JSON\u3001RegExp\u3001GraphQL \u548c Markdown \u7b49\u683c\u5f0f\u7684\u89e3\u6790\u3002<\/p>\n<h4 data-id=\"heading-117\">16.6\u00a0<a title=\"https:\/\/typedoc.org\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Ftypedoc.org%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeDoc<\/a><\/h4>\n<blockquote><p>\u7b80\u4ecb\uff1aTypeDoc \u7528\u4e8e\u5c06 TypeScript \u6e90\u4ee3\u7801\u4e2d\u7684\u6ce8\u91ca\u8f6c\u6362\u4e3a HTML \u6587\u6863\u6216 JSON \u6a21\u578b\u3002\u5b83\u53ef\u7075\u6d3b\u6269\u5c55\uff0c\u5e76\u652f\u6301\u591a\u79cd\u914d\u7f6e\u3002<\/p>\n<p>\u5728\u7ebf\u5730\u5740\uff1a<a title=\"https:\/\/typedoc.org\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Ftypedoc.org%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">typedoc.org\/<\/a><\/p><\/blockquote>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p9-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/44b7ffe42d3a426d9c30e23b59f8db86~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<h4 data-id=\"heading-118\">16.7\u00a0<a title=\"https:\/\/typescript-eslint.io\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Ftypescript-eslint.io%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript ESLint<\/a><\/h4>\n<blockquote><p>\u7b80\u4ecb\uff1a\u4f7f\u7528\u00a0<a title=\"https:\/\/typescript-eslint.io\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Ftypescript-eslint.io%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript ESLint<\/a>\u00a0\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\u89c4\u8303\u4ee3\u7801\u8d28\u91cf\uff0c\u63d0\u9ad8\u56e2\u961f\u5f00\u53d1\u6548\u7387\u3002<\/p>\n<p>\u5728\u7ebf\u5730\u5740\uff1a<a title=\"https:\/\/typescript-eslint.io\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Ftypescript-eslint.io%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">typescript-eslint.io\/<\/a><\/p><\/blockquote>\n<p><img decoding=\"async\" class=\"medium-zoom-image\" src=\"https:\/\/p3-juejin.byteimg.com\/tos-cn-i-k3u1fbpfcp\/ba2dc2fa049340d3bde452f6ebf2554f~tplv-k3u1fbpfcp-zoom-in-crop-mark:1304:0:0:0.awebp\" alt=\"\" \/><\/p>\n<p>\u5bf9\u00a0<a title=\"https:\/\/typescript-eslint.io\/\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Ftypescript-eslint.io%2F\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript ESLint<\/a>\u00a0\u9879\u76ee\u611f\u5174\u8da3\u4e14\u60f3\u5728\u9879\u76ee\u4e2d\u5e94\u7528\u7684\u5c0f\u4f19\u4f34\uff0c\u53ef\u4ee5\u53c2\u8003\u00a0<a title=\"https:\/\/juejin.cn\/post\/6844903880006844424\" href=\"https:\/\/juejin.cn\/post\/6844903880006844424\" target=\"_blank\" rel=\"noopener\">\u201c\u5728Typescript\u9879\u76ee\u4e2d\uff0c\u5982\u4f55\u4f18\u96c5\u7684\u4f7f\u7528ESLint\u548cPrettier\u201d<\/a>\u00a0\u8fd9\u7bc7\u6587\u7ae0\u3002<\/p>\n<p>\u80fd\u575a\u6301\u770b\u5230\u8fd9\u91cc\u7684\u5c0f\u4f19\u4f34\u90fd\u662f \u201c\u771f\u7231\u201d\uff0c\u5982\u679c\u4f60\u8fd8\u610f\u72b9\u672a\u5c3d\uff0c\u90a3\u5c31\u6765\u770b\u770b\u672c\u4eba\u6574\u7406\u7684 Github \u4e0a 1.8K+ \u7684\u5f00\u6e90\u9879\u76ee\uff1a<a title=\"https:\/\/github.com\/semlinker\/awesome-typescript\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fgithub.com%2Fsemlinker%2Fawesome-typescript\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">awesome-typescript<\/a>\u3002<\/p>\n<h3 data-id=\"heading-119\">\u5341\u4e03\u3001\u53c2\u8003\u8d44\u6e90<\/h3>\n<ul>\n<li><a title=\"https:\/\/mariusschulz.com\/blog\/the-unknown-type-in-typescript\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fmariusschulz.com%2Fblog%2Fthe-unknown-type-in-typescript\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">mariusschulz &#8211; the-unknown-type-in-typescript<\/a><\/li>\n<li><a title=\"https:\/\/jkchao.github.io\/typescript-book-chinese\/project\/compilationContext.html#tsconfig-json\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fjkchao.github.io%2Ftypescript-book-chinese%2Fproject%2FcompilationContext.html%23tsconfig-json\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">\u6df1\u5165\u7406\u89e3 TypeScript &#8211; \u7f16\u8bd1\u4e0a\u4e0b\u6587<\/a><\/li>\n<li><a title=\"https:\/\/www.typescriptlang.org\/docs\/handbook\/release-notes\/typescript-4-0.html\" href=\"https:\/\/link.juejin.cn\/?target=https%3A%2F%2Fwww.typescriptlang.org%2Fdocs%2Fhandbook%2Frelease-notes%2Ftypescript-4-0.html\" target=\"_blank\" rel=\"nofollow noopener noreferrer\">TypeScript 4.0<\/a><\/li>\n<li>TypeScript Quickly<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"tag-list-box\" data-v-409ef5ee=\"\">\n<div class=\"tag-list\" data-v-409ef5ee=\"\">\n<div class=\"tag-list-title\" data-v-409ef5ee=\"\">\u5206\u7c7b\uff1a<\/div>\n<p><a class=\"item category-item\" href=\"https:\/\/juejin.cn\/frontend\" target=\"_blank\" rel=\"noopener\" data-v-409ef5ee=\"\"><span class=\"tag-title\" data-v-409ef5ee=\"\">\u524d\u7aef<\/span><\/a><\/div>\n<div class=\"tag-list\" data-v-409ef5ee=\"\">\n<div class=\"tag-list-title\" data-v-409ef5ee=\"\">\u6807\u7b7e\uff1a<\/div>\n<div class=\"tag-list-container\" data-v-409ef5ee=\"\"><a class=\"item tag-item\" href=\"https:\/\/juejin.cn\/tag\/%E5%89%8D%E7%AB%AF\" target=\"_blank\" rel=\"noopener\" data-v-409ef5ee=\"\"><span class=\"tag-title\" data-v-409ef5ee=\"\">\u524d\u7aef<\/span><\/a><a class=\"item tag-item\" href=\"https:\/\/juejin.cn\/tag\/TypeScript\" target=\"_blank\" rel=\"noopener\" data-v-409ef5ee=\"\"><span class=\"tag-title\" data-v-409ef5ee=\"\">TypeScript<\/span><\/a><\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\u539f\u6587\u5730\u5740 \u5173\u6ce8 \u963f\u5b9d\u54e5\u7b2c\u4e00\u6b21\u4f7f\u7528\u00a0Typ<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"colormag_page_container_layout":"default_layout","colormag_page_sidebar_layout":"default_layout","footnotes":""},"categories":[24],"tags":[121],"class_list":["post-5822","post","type-post","status-publish","format-standard","hentry","category-value_docs","tag-05-"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/5822","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/comments?post=5822"}],"version-history":[{"count":0,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/5822\/revisions"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=5822"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=5822"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=5822"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}