{"id":1417,"date":"2024-06-02T23:02:13","date_gmt":"2024-06-02T23:02:13","guid":{"rendered":""},"modified":"2024-06-05T06:12:46","modified_gmt":"2024-06-04T22:12:46","slug":"typescript-%e4%b9%8b%e5%9f%ba%e7%a1%80%e5%85%a5%e9%97%a8","status":"publish","type":"post","link":"https:\/\/www.lccc.top\/?p=1417","title":{"rendered":"TypeScript \u4e4b\u57fa\u7840\u5165\u95e8"},"content":{"rendered":"<td class=\"d-block comment-body markdown-body  js-comment-body\">\n<h2 dir=\"auto\">\u524d\u8a00<\/h2>\n<p dir=\"auto\">TypeScript \u7684\u5b98\u65b9\u6587\u6863\u65e9\u5df2\u66f4\u65b0\uff0c\u4f46\u6211\u80fd\u627e\u5230\u7684\u4e2d\u6587\u6587\u6863\u90fd\u8fd8\u505c\u7559\u5728\u6bd4\u8f83\u8001\u7684\u7248\u672c\u3002\u6240\u4ee5\u5bf9\u5176\u4e2d\u65b0\u589e\u4ee5\u53ca\u4fee\u8ba2\u8f83\u591a\u7684\u4e00\u4e9b\u7ae0\u8282\u8fdb\u884c\u4e86\u7ffb\u8bd1\u6574\u7406\u3002<\/p>\n<p dir=\"auto\">\u672c\u7bc7\u6574\u7406\u81ea TypeScript Handbook \u4e2d \u300c<a href=\"https:\/\/www.typescriptlang.org\/docs\/handbook\/2\/basic-types.html\" rel=\"nofollow\">The Basics<\/a>\u300d \u7ae0\u8282\u3002<\/p>\n<p dir=\"auto\">\u672c\u6587\u5e76\u4e0d\u4e25\u683c\u6309\u7167\u539f\u6587\u7ffb\u8bd1\uff0c\u5bf9\u90e8\u5206\u5185\u5bb9\u4e5f\u505a\u4e86\u89e3\u91ca\u8865\u5145\u3002<\/p>\n<h2 dir=\"auto\">\u6b63\u6587<\/h2>\n<p dir=\"auto\">JavaScript \u7684\u6bcf\u4e2a\u503c\u6267\u884c\u4e0d\u540c\u7684\u64cd\u4f5c\u65f6\u4f1a\u6709\u4e0d\u540c\u7684\u884c\u4e3a\u3002\u8fd9\u542c\u8d77\u6765\u6709\u70b9\u62bd\u8c61\uff0c\u6240\u4ee5\u8ba9\u6211\u4eec\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u5047\u8bbe\u6211\u4eec\u6709\u4e00\u4e2a\u540d\u4e3a <code class=\"notranslate\">message<\/code> \u7684\u53d8\u91cf\uff0c\u8bd5\u60f3\u6211\u4eec\u53ef\u4ee5\u505a\u54ea\u4e9b\u64cd\u4f5c\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"\/\/ Accessing the property 'toLowerCase'\n\/\/ on 'message' and then calling it\nmessage.toLowerCase();\n\/\/ Calling 'message'\nmessage();\"><\/p>\n<pre class=\"notranslate\"><span class=\"pl-c\">\/\/ Accessing the property 'toLowerCase'<\/span>\n<span class=\"pl-c\">\/\/ on 'message' and then calling it<\/span>\n<span class=\"pl-s1\">message<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toLowerCase<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-c\">\/\/ Calling 'message'<\/span>\n<span class=\"pl-en\">message<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u7b2c\u4e00\u884c\u4ee3\u7801\u662f\u83b7\u53d6\u5c5e\u6027 <code class=\"notranslate\">toLowerCase<\/code> \uff0c\u7136\u540e\u8c03\u7528\u5b83\u3002\u7b2c\u4e8c\u884c\u4ee3\u7801\u5219\u662f\u76f4\u63a5\u8c03\u7528 <code class=\"notranslate\">message<\/code> \u3002<\/p>\n<p dir=\"auto\">\u4f46\u5176\u5b9e\u6211\u4eec\u8fde <code class=\"notranslate\">message<\/code> \u7684\u503c\u90fd\u4e0d\u77e5\u9053\u5462\uff0c\u81ea\u7136\u4e5f\u4e0d\u77e5\u9053\u8fd9\u6bb5\u4ee3\u7801\u7684\u6267\u884c\u7ed3\u679c\u3002\u6bcf\u4e00\u4e2a\u64cd\u4f5c\u884c\u4e3a\u90fd\u5148\u53d6\u51b3\u4e8e\u6211\u4eec\u6709\u4ec0\u4e48\u6837\u7684\u503c\u3002<\/p>\n<ul dir=\"auto\">\n<li><code class=\"notranslate\">message<\/code> \u662f\u53ef\u8c03\u7528\u7684\u5417\uff1f<\/li>\n<li><code class=\"notranslate\">message<\/code> \u6709\u4e00\u4e2a\u540d\u4e3a <code class=\"notranslate\">toLowerCase<\/code> \u7684\u5c5e\u6027\u5417\uff1f<\/li>\n<li>\u5982\u679c\u6709\uff0c<code class=\"notranslate\">toLowerCase<\/code> \u662f\u53ef\u4ee5\u88ab\u8c03\u7528\u7684\u5417\uff1f<\/li>\n<li>\u5982\u679c\u8fd9\u4e9b\u503c\u90fd\u53ef\u4ee5\u88ab\u8c03\u7528\uff0c\u5b83\u4eec\u4f1a\u8fd4\u56de\u4ec0\u4e48\uff1f<\/li>\n<\/ul>\n<p dir=\"auto\">\u5f53\u6211\u4eec\u5199 JavaScript \u7684\u65f6\u5019\uff0c\u8fd9\u4e9b\u95ee\u9898\u7684\u7b54\u6848\u6211\u4eec\u9700\u8981\u8c28\u8bb0\u5728\u5fc3\uff0c\u540c\u65f6\u8fd8\u8981\u671f\u671b\u5904\u7406\u597d\u6240\u6709\u7684\u7ec6\u8282\u3002<\/p>\n<p dir=\"auto\">\u8ba9\u6211\u4eec\u5047\u8bbe <code class=\"notranslate\">message<\/code> \u662f\u8fd9\u6837\u5b9a\u4e49\u7684\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='const message = \"Hello World!\";'>\n<pre class=\"notranslate\"><span class=\"pl-k\">const<\/span> <span class=\"pl-s1\">message<\/span> <span class=\"pl-c1\">=<\/span> <span class=\"pl-s\">\"Hello World!\"<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u4f60\u5b8c\u5168\u53ef\u4ee5\u731c\u5230\u8fd9\u6bb5\u4ee3\u7801\u7684\u7ed3\u679c\uff0c\u5982\u679c\u6211\u4eec\u5c1d\u8bd5\u8fd0\u884c <code class=\"notranslate\">message.toLowerCase()<\/code> \uff0c\u6211\u4eec\u53ef\u4ee5\u5f97\u5230\u8fd9\u6bb5\u5b57\u7b26\u7684\u5c0f\u5199\u5f62\u5f0f\u3002<\/p>\n<p dir=\"auto\">\u90a3\u7b2c\u4e8c\u6bb5\u4ee3\u7801\u5462\uff1f\u5982\u679c\u4f60\u5bf9 JavaScript \u6bd4\u8f83\u719f\u6089\uff0c\u4f60\u80af\u5b9a\u77e5\u9053\u4f1a\u62a5\u5982\u4e0b\u9519\u8bef\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"TypeError: message is not a function\">\n<pre class=\"notranslate\"><span class=\"pl-smi\">TypeError<\/span>: <span class=\"pl-s1\">message<\/span> <span class=\"pl-s1\">is<\/span> <span class=\"pl-s1\">not<\/span> <span class=\"pl-s1\">a<\/span> <span class=\"pl-k\">function<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u5982\u679c\u6211\u4eec\u80fd\u907f\u514d\u8fd9\u6837\u7684\u62a5\u9519\u5c31\u597d\u4e86\u3002<\/p>\n<p dir=\"auto\">\u5f53\u6211\u4eec\u8fd0\u884c\u4ee3\u7801\u7684\u65f6\u5019\uff0cJavaScript \u4f1a\u5728\u8fd0\u884c\u65f6\u5148\u7b97\u51fa\u503c\u7684\u7c7b\u578b\uff08type\uff09\uff0c\u7136\u540e\u518d\u51b3\u5b9a\u5e72\u4ec0\u4e48\u3002\u6240\u8c13\u503c\u7684\u7c7b\u578b\uff0c\u4e5f\u5305\u62ec\u4e86\u8fd9\u4e2a\u503c\u6709\u4ec0\u4e48\u884c\u4e3a\u548c\u80fd\u529b\u3002\u5f53\u7136 <code class=\"notranslate\">TypeError<\/code> \u4e5f\u4f1a\u6697\u793a\u6027\u7684\u544a\u8bc9\u6211\u4eec\u4e00\u70b9\uff0c\u6bd4\u5982\u5728\u8fd9\u4e2a\u4f8b\u5b50\u91cc\uff0c\u5b83\u544a\u8bc9\u6211\u4eec\u5b57\u7b26\u4e32 <code class=\"notranslate\">Hello World<\/code> \u4e0d\u80fd\u4f5c\u4e3a\u51fd\u6570\u88ab\u8c03\u7528\u3002<\/p>\n<p dir=\"auto\">\u5bf9\u4e8e\u4e00\u4e9b\u503c\uff0c\u6bd4\u5982\u57fa\u672c\u503c <code class=\"notranslate\">string<\/code> \u548c <code class=\"notranslate\">number<\/code>\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528 <code class=\"notranslate\">typeof<\/code> \u8fd0\u7b97\u7b26\u786e\u8ba4\u4ed6\u4eec\u7684\u7c7b\u578b\u3002\u4f46\u662f\u5bf9\u4e8e\u5176\u4ed6\u7684\u6bd4\u5982\u51fd\u6570\uff0c\u5c31\u6ca1\u6709\u5bf9\u5e94\u7684\u65b9\u6cd5\u53ef\u4ee5\u786e\u8ba4\u4ed6\u4eec\u7684\u7c7b\u578b\u4e86\uff0c\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u601d\u8003\u8fd9\u4e2a\u51fd\u6570\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"function fn(x) {\n  return x.flip();\n}\"><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">function<\/span> <span class=\"pl-en\">fn<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s1\">x<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-k\">return<\/span> <span class=\"pl-s1\">x<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">flip<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-kos\">}<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u6211\u4eec\u901a\u8fc7\u9605\u8bfb\u4ee3\u7801\u53ef\u4ee5\u77e5\u9053\uff0c\u51fd\u6570\u53ea\u6709\u88ab\u4f20\u5165\u4e00\u4e2a\u62e5\u6709\u53ef\u8c03\u7528\u7684 <code class=\"notranslate\">flip<\/code> \u5c5e\u6027\u7684\u5bf9\u8c61\uff0c\u624d\u4f1a\u6b63\u5e38\u6267\u884c\u3002\u4f46\u662f JavaScript \u5728\u4ee3\u7801\u6267\u884c\u65f6\uff0c\u5e76\u4e0d\u4f1a\u628a\u8fd9\u4e2a\u4fe1\u606f\u4f53\u73b0\u51fa\u6765\u3002\u5728 JavaScript \u4e2d\uff0c\u552f\u4e00\u53ef\u4ee5\u77e5\u9053 <code class=\"notranslate\">fn<\/code> \u5728\u88ab\u4f20\u5165\u7279\u6b8a\u7684\u503c\u65f6\u4f1a\u53d1\u751f\u4ec0\u4e48\uff0c\u5c31\u662f\u8c03\u7528\u5b83\uff0c\u7136\u540e\u770b\u4f1a\u53d1\u751f\u4ec0\u4e48\u3002\u8fd9\u79cd\u884c\u4e3a\u8ba9\u4f60\u5f88\u96be\u5728\u4ee3\u7801\u8fd0\u884c\u524d\u5c31\u9884\u6d4b\u4ee3\u7801\u6267\u884c\u7ed3\u679c\uff0c\u8fd9\u4e5f\u610f\u5473\u7740\u5f53\u4f60\u5199\u4ee3\u7801\u7684\u65f6\u5019\uff0c\u4f60\u4f1a\u66f4\u96be\u77e5\u9053\u4f60\u7684\u4ee3\u7801\u4f1a\u53d1\u751f\u4ec0\u4e48\u3002<\/p>\n<p dir=\"auto\">\u4ece\u8fd9\u4e2a\u89d2\u5ea6\u6765\u770b\uff0c\u7c7b\u578b\u5c31\u662f\u63cf\u8ff0\u4ec0\u4e48\u6837\u7684\u503c\u53ef\u4ee5\u88ab\u4f20\u9012\u7ed9 <code class=\"notranslate\">fn<\/code>\uff0c\u4ec0\u4e48\u6837\u7684\u503c\u5219\u4f1a\u5bfc\u81f4\u5d29\u6e83\u3002JavaScript \u4ec5\u4ec5\u63d0\u4f9b\u4e86\u52a8\u6001\u7c7b\u578b\uff08dynamic typing\uff09\uff0c\u8fd9\u9700\u8981\u4f60\u5148\u8fd0\u884c\u4ee3\u7801\u7136\u540e\u518d\u770b\u4f1a\u53d1\u751f\u4ec0\u4e48\u3002<\/p>\n<p dir=\"auto\">\u66ff\u4ee3\u65b9\u6848\u5c31\u662f\u4f7f\u7528\u9759\u6001\u7c7b\u578b\u7cfb\u7edf\uff08static type system\uff09\uff0c\u5728\u4ee3\u7801\u8fd0\u884c\u4e4b\u524d\u5c31\u9884\u6d4b\u9700\u8981\u4ec0\u4e48\u6837\u7684\u4ee3\u7801\u3002<\/p>\n<h2 dir=\"auto\">\u9759\u6001\u7c7b\u578b\u68c0\u67e5\uff08Static type-checking\uff09<\/h2>\n<p dir=\"auto\">\u8ba9\u6211\u4eec\u518d\u56de\u60f3\u4e0b\u8fd9\u4e2a\u5c06 <code class=\"notranslate\">string<\/code> \u4f5c\u4e3a\u51fd\u6570\u8fdb\u884c\u8c03\u7528\u800c\u4ea7\u751f\u7684 <code class=\"notranslate\">TypeError<\/code> \uff0c\u5927\u90e8\u5206\u7684\u4eba\u5e76\u4e0d\u559c\u6b22\u5728\u8fd0\u884c\u4ee3\u7801\u7684\u65f6\u5019\u5f97\u5230\u62a5\u9519\u3002\u8fd9\u4e9b\u4f1a\u88ab\u8ba4\u4e3a\u662f bug\u3002\u5f53\u6211\u4eec\u5199\u65b0\u4ee3\u7801\u7684\u65f6\u5019\uff0c\u6211\u4eec\u4e5f\u5c3d\u529b\u907f\u514d\u4ea7\u751f\u65b0\u7684 bug\u3002<\/p>\n<p dir=\"auto\">\u5982\u679c\u6211\u4eec\u6dfb\u52a0\u4e00\u70b9\u4ee3\u7801\uff0c\u4fdd\u5b58\u6587\u4ef6\uff0c\u7136\u540e\u91cd\u65b0\u8fd0\u884c\u4ee3\u7801\uff0c\u5c31\u80fd\u7acb\u523b\u770b\u5230\u9519\u8bef\uff0c\u6211\u4eec\u53ef\u4ee5\u5f88\u5feb\u7684\u5b9a\u4f4d\u5230\u95ee\u9898\uff0c\u4f46\u4e5f\u5e76\u4e0d\u603b\u662f\u8fd9\u6837\uff0c\u6bd4\u5982\u5982\u679c\u6211\u4eec\u6ca1\u6709\u505a\u5145\u5206\u7684\u6d4b\u8bd5\uff0c\u6211\u4eec\u5c31\u9047\u4e0d\u5230\u53ef\u80fd\u51fa\u9519\u7684\u60c5\u51b5\u3002\u6216\u8005\u5982\u679c\u6211\u4eec\u8db3\u591f\u5e78\u8fd0\u770b\u5230\u4e86\u8fd9\u4e2a\u9519\u8bef\uff0c\u6211\u4eec\u4e5f\u8bb8\u4e0d\u5f97\u4e0d\u505a\u4e00\u4e2a\u5927\u7684\u91cd\u6784\uff0c\u7136\u540e\u6dfb\u52a0\u5f88\u591a\u4e0d\u540c\u7684\u4ee3\u7801\uff0c\u624d\u80fd\u627e\u51fa\u95ee\u9898\u6240\u5728\u3002<\/p>\n<p dir=\"auto\">\u7406\u60f3\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u5e94\u8be5\u6709\u4e00\u4e2a\u5de5\u5177\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\uff0c\u5728\u4ee3\u7801\u8fd0\u884c\u4e4b\u524d\u5c31\u627e\u5230\u9519\u8bef\u3002\u8fd9\u5c31\u662f\u9759\u6001\u7c7b\u578b\u68c0\u67e5\u5668\u6bd4\u5982 TypeScript \u505a\u7684\u4e8b\u60c5\u3002\u9759\u6001\u7c7b\u578b\u7cfb\u7edf\uff08Static types systems\uff09\u63cf\u8ff0\u4e86\u503c\u5e94\u6709\u7684\u7ed3\u6784\u548c\u884c\u4e3a\u3002\u4e00\u4e2a\u50cf TypeScript \u7684\u7c7b\u578b\u68c0\u67e5\u5668\u4f1a\u5229\u7528\u8fd9\u4e2a\u4fe1\u606f\uff0c\u5e76\u4e14\u5728\u53ef\u80fd\u4f1a\u51fa\u9519\u7684\u65f6\u5019\u544a\u8bc9\u6211\u4eec\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"const message = &quot;hello!&quot;;\n \nmessage();\n\n\/\/ This expression is not callable.\n\/\/ Type 'String' has no call signatures.\"><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">const<\/span> <span class=\"pl-s1\">message<\/span> <span class=\"pl-c1\">=<\/span> <span class=\"pl-s\">\"hello!\"<\/span><span class=\"pl-kos\">;<\/span>\n \n<span class=\"pl-en\">message<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n\n<span class=\"pl-c\">\/\/ This expression is not callable.<\/span>\n<span class=\"pl-c\">\/\/ Type 'String' has no call signatures.<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0cTypeScript \u4f1a\u5728\u8fd0\u884c\u4e4b\u524d\u5c31\u4f1a\u629b\u51fa\u9519\u8bef\u4fe1\u606f\u3002<\/p>\n<h2 dir=\"auto\">\u975e\u5f02\u5e38\u5931\u8d25\uff08Non-exception \u5931\u8d25\uff09<\/h2>\n<p dir=\"auto\">\u81f3\u4eca\u4e3a\u6b62\uff0c\u6211\u4eec\u5df2\u7ecf\u8ba8\u8bba\u7684\u90fd\u662f\u8fd0\u884c\u65f6\u7684\u9519\u8bef\uff0c\u6240\u8c13\u8fd0\u884c\u65f6\u9519\u8bef\uff0c\u5c31\u662f JavaScript \u4f1a\u5728\u8fd0\u884c\u65f6\u544a\u8bc9\u6211\u4eec\u5b83\u8ba4\u4e3a\u7684\u4e00\u4e9b\u6ca1\u6709\u610f\u4e49\u7684\u4e8b\u60c5\u3002\u8fd9\u4e9b\u4e8b\u60c5\u4e4b\u6240\u4ee5\u4f1a\u51fa\u73b0\uff0c\u662f\u56e0\u4e3a <a href=\"https:\/\/tc39.github.io\/ecma262\/\" rel=\"nofollow\">ECMAScript \u89c4\u8303<\/a>\u5df2\u7ecf\u660e\u786e\u7684\u58f0\u660e\u4e86\u8fd9\u4e9b\u5f02\u5e38\u65f6\u7684\u884c\u4e3a\u3002<\/p>\n<p dir=\"auto\">\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u89c4\u8303\u89c4\u5b9a\uff0c\u5f53\u8c03\u7528\u4e00\u4e2a\u975e\u53ef\u8c03\u7528\u7684\u4e1c\u897f\u65f6\u5e94\u8be5\u629b\u51fa\u4e00\u4e2a\u9519\u8bef\u3002\u4e5f\u8bb8\u542c\u8d77\u6765\u50cf\u662f\u7406\u6240\u5f53\u7136\u7684\uff0c\u7531\u6b64\u4f60\u53ef\u80fd\u8ba4\u4e3a\uff0c\u5982\u679c\u83b7\u53d6\u4e00\u4e2a\u5bf9\u8c61\u4e0d\u5b58\u5728\u7684\u5c5e\u6027\u4e5f\u5e94\u8be5\u629b\u51fa\u4e00\u4e2a\u9519\u8bef\uff0c\u4f46\u662f JavaScript \u5e76\u4e0d\u4f1a\u8fd9\u6837\uff0c\u5b83\u4e0d\u62a5\u9519\uff0c\u8fd8\u8fd4\u56de\u503c <code class=\"notranslate\">undefined<\/code>\u3002<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='const user = {\n  name: \"Daniel\",\n  age: 26,\n};\nuser.location; \/\/ returns undefined'><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">const<\/span> <span class=\"pl-s1\">user<\/span> <span class=\"pl-c1\">=<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-c1\">name<\/span>: <span class=\"pl-s\">\"Daniel\"<\/span><span class=\"pl-kos\">,<\/span>\n  <span class=\"pl-c1\">age<\/span>: <span class=\"pl-c1\">26<\/span><span class=\"pl-kos\">,<\/span>\n<span class=\"pl-kos\">}<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-s1\">user<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-c1\">location<\/span><span class=\"pl-kos\">;<\/span> <span class=\"pl-c\">\/\/ returns undefined<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u4e00\u4e2a\u9759\u6001\u7c7b\u578b\u9700\u8981\u6807\u8bb0\u51fa\u54ea\u4e9b\u4ee3\u7801\u662f\u4e00\u4e2a\u9519\u8bef\uff0c\u54ea\u6015\u5b9e\u9645\u751f\u6548\u7684 JavaScript \u5e76\u4e0d\u4f1a\u7acb\u523b\u62a5\u9519\u3002\u5728 TypeScript \u4e2d\uff0c\u4e0b\u9762\u7684\u4ee3\u7801\u4f1a\u4ea7\u751f\u4e00\u4e2a <code class=\"notranslate\">location<\/code> \u4e0d\u5b58\u5728\u7684\u62a5\u9519\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"const user = {\n  name: &quot;Daniel&quot;,\n  age: 26,\n};\n \nuser.location;\n\/\/ Property 'location' does not exist on type '{ name: string; age: number; }'.\"><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">const<\/span> <span class=\"pl-s1\">user<\/span> <span class=\"pl-c1\">=<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-c1\">name<\/span>: <span class=\"pl-s\">\"Daniel\"<\/span><span class=\"pl-kos\">,<\/span>\n  <span class=\"pl-c1\">age<\/span>: <span class=\"pl-c1\">26<\/span><span class=\"pl-kos\">,<\/span>\n<span class=\"pl-kos\">}<\/span><span class=\"pl-kos\">;<\/span>\n \n<span class=\"pl-s1\">user<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-c1\">location<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-c\">\/\/ Property 'location' does not exist on type '{ name: string; age: number; }'.<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u5c3d\u7ba1\u6709\u65f6\u5019\u8fd9\u610f\u5473\u7740\u4f60\u9700\u8981\u5728\u8868\u8fbe\u7684\u65f6\u5019\u4e0a\u505a\u4e00\u4e9b\u53d6\u820d\uff0c\u4f46\u76ee\u7684\u8fd8\u662f\u627e\u51fa\u6211\u4eec\u9879\u76ee\u4e2d\u4e00\u4e9b\u5408\u7406\u7684\u9519\u8bef\u3002TypeScript \u73b0\u5728\u5df2\u7ecf\u53ef\u4ee5\u6355\u83b7\u5f88\u591a\u5408\u7406\u7684\u9519\u8bef\u3002<\/p>\n<p dir=\"auto\">\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u6bd4\u5982\u62fc\u5199\u9519\u8bef\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='const announcement = \"Hello World!\";\n \n\/\/ How quickly can you spot the typos?\nannouncement.toLocaleLowercase();\nannouncement.toLocalLowerCase();\n \n\/\/ We probably meant to write this...\nannouncement.toLocaleLowerCase();'><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">const<\/span> <span class=\"pl-s1\">announcement<\/span> <span class=\"pl-c1\">=<\/span> <span class=\"pl-s\">\"Hello World!\"<\/span><span class=\"pl-kos\">;<\/span>\n \n<span class=\"pl-c\">\/\/ How quickly can you spot the typos?<\/span>\n<span class=\"pl-s1\">announcement<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toLocaleLowercase<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-s1\">announcement<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toLocalLowerCase<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n \n<span class=\"pl-c\">\/\/ We probably meant to write this...<\/span>\n<span class=\"pl-s1\">announcement<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toLocaleLowerCase<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u51fd\u6570\u672a\u88ab\u8c03\u7528\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"function flipCoin() {\n  \/\/ Meant to be Math.random()\n  return Math.random &lt; 0.5;\n\/\/ Operator '&lt;' cannot be applied to types '() =&gt; number' and 'number'.\n}\"><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">function<\/span> <span class=\"pl-en\">flipCoin<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-c\">\/\/ Meant to be Math.random()<\/span>\n  <span class=\"pl-k\">return<\/span> <span class=\"pl-smi\">Math<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-c1\">random<\/span> <span class=\"pl-c1\">&lt;<\/span> <span class=\"pl-c1\">0.5<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-c\">\/\/ Operator '&lt;' cannot be applied to types '() =&gt; number' and 'number'.<\/span>\n<span class=\"pl-kos\">}<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u57fa\u672c\u7684\u903b\u8f91\u9519\u8bef\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"const value = Math.random() &lt; 0.5 ? &quot;a&quot; : &quot;b&quot;;\nif (value !== &quot;a&quot;) {\n  \/\/ ...\n} else if (value === &quot;b&quot;) {\n  \/\/ This condition will always return 'false' since the types '&quot;a&quot;' and '&quot;b&quot;' have no overlap.\n  \/\/ Oops, unreachable\n}\"><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">const<\/span> <span class=\"pl-s1\">value<\/span> <span class=\"pl-c1\">=<\/span> <span class=\"pl-smi\">Math<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">random<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-c1\">&lt;<\/span> <span class=\"pl-c1\">0.5<\/span> ? <span class=\"pl-s\">\"a\"<\/span> : <span class=\"pl-s\">\"b\"<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-k\">if<\/span> <span class=\"pl-kos\">(<\/span><span class=\"pl-s1\">value<\/span> <span class=\"pl-c1\">!==<\/span> <span class=\"pl-s\">\"a\"<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-c\">\/\/ ...<\/span>\n<span class=\"pl-kos\">}<\/span> <span class=\"pl-k\">else<\/span> <span class=\"pl-k\">if<\/span> <span class=\"pl-kos\">(<\/span><span class=\"pl-s1\">value<\/span> <span class=\"pl-c1\">===<\/span> <span class=\"pl-s\">\"b\"<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-c\">\/\/ This condition will always return 'false' since the types '\"a\"' and '\"b\"' have no overlap.<\/span>\n  <span class=\"pl-c\">\/\/ Oops, unreachable<\/span>\n<span class=\"pl-kos\">}<\/span><\/pre>\n<\/div>\n<h2 dir=\"auto\">\u7c7b\u578b\u5de5\u5177\uff08Types for Tooling\uff09<\/h2>\n<p dir=\"auto\">TypeScript \u4e0d\u4ec5\u5728\u6211\u4eec\u72af\u9519\u7684\u65f6\u5019\uff0c\u53ef\u4ee5\u627e\u51fa\u9519\u8bef\uff0c\u8fd8\u53ef\u4ee5\u9632\u6b62\u6211\u4eec\u72af\u9519\u3002<\/p>\n<p dir=\"auto\">\u7c7b\u578b\u68c0\u67e5\u5668\u56e0\u4e3a\u6709\u7c7b\u578b\u4fe1\u606f\uff0c\u53ef\u4ee5\u68c0\u67e5\u6bd4\u5982\u8bf4\u662f\u5426\u6b63\u786e\u83b7\u53d6\u4e86\u4e00\u4e2a\u53d8\u91cf\u7684\u5c5e\u6027\u3002\u4e5f\u6b63\u662f\u56e0\u4e3a\u6709\u8fd9\u4e2a\u4fe1\u606f\uff0c\u5b83\u4e5f\u53ef\u4ee5\u5728\u4f60\u8f93\u5165\u7684\u65f6\u5019\uff0c\u5217\u51fa\u4f60\u53ef\u80fd\u60f3\u8981\u4f7f\u7528\u7684\u5c5e\u6027\u3002<\/p>\n<p dir=\"auto\">\u8fd9\u610f\u5473\u7740 TypeScript \u5bf9\u4f60\u7f16\u5199\u4ee3\u7801\u4e5f\u5f88\u6709\u5e2e\u52a9\uff0c\u6838\u5fc3\u7684\u7c7b\u578b\u68c0\u67e5\u5668\u4e0d\u4ec5\u53ef\u4ee5\u63d0\u4f9b\u9519\u8bef\u4fe1\u606f\uff0c\u8fd8\u53ef\u4ee5\u63d0\u4f9b\u4ee3\u7801\u8865\u5168\u529f\u80fd\u3002\u8fd9\u5c31\u662f TypeScript \u5728\u5de5\u5177\u65b9\u9762\u7684\u4f5c\u7528\u3002<br \/>\n<a target=\"_blank\" rel=\"noopener noreferrer nofollow\" href=\"\/\/www.lccc.top\/wp-content\/uploads\/pic\/mqyqingfen\/a4af96391d695caf89e6f2c01300a82b1f621bb9.jpg\"><img decoding=\"async\" src=\"\/\/www.lccc.top\/wp-content\/uploads\/pic\/mqyqingfen\/a4af96391d695caf89e6f2c01300a82b1f621bb9.jpg\" alt=\"\" data-canonical-src=\"https:\/\/cdn.jsdelivr.net\/gh\/mqyqingfeng\/picture\/image.png\" style=\"max-width: 100%;\"><\/a><\/p>\n<p dir=\"auto\">TypeScript \u7684\u529f\u80fd\u5f88\u5f3a\u5927\uff0c\u9664\u4e86\u5728\u4f60\u8f93\u5165\u7684\u65f6\u5019\u63d0\u4f9b\u8865\u5168\u548c\u9519\u8bef\u4fe1\u606f\u3002\u8fd8\u53ef\u4ee5\u652f\u6301\u201c\u5feb\u901f\u4fee\u590d\u201d\u529f\u80fd\uff0c\u5373\u81ea\u52a8\u7684\u4fee\u590d\u9519\u8bef\uff0c\u91cd\u6784\u6210\u7ec4\u7ec7\u6e05\u6670\u7684\u4ee3\u7801\u3002\u540c\u65f6\u4e5f\u652f\u6301\u5bfc\u822a\u529f\u80fd\uff0c\u6bd4\u5982\u8df3\u8f6c\u5230\u53d8\u91cf\u5b9a\u4e49\u7684\u5730\u65b9\uff0c\u6216\u8005\u627e\u5230\u4e00\u4e2a\u7ed9\u5b9a\u7684\u53d8\u91cf\u6240\u6709\u7684\u5f15\u7528\u3002<\/p>\n<p dir=\"auto\">\u6240\u6709\u8fd9\u4e9b\u529f\u80fd\u90fd\u5efa\u7acb\u5728\u7c7b\u578b\u68c0\u67e5\u5668\u4e0a\uff0c\u5e76\u4e14\u8de8\u5e73\u53f0\u652f\u6301\u3002<a href=\"https:\/\/github.com\/Microsoft\/TypeScript\/wiki\/TypeScript-Editor-Support\">\u6709\u53ef\u80fd\u4f60\u6700\u559c\u6b22\u7684\u7f16\u8f91\u5668<\/a>\u5df2\u7ecf\u652f\u6301\u4e86 TypeScript\u3002<\/p>\n<h2 dir=\"auto\"><code class=\"notranslate\">tsc<\/code> TypeScript \u7f16\u8bd1\u5668\uff08tsc\uff0cthe TypeScript compiler\uff09<\/h2>\n<p dir=\"auto\">\u81f3\u4eca\u6211\u4eec\u53ea\u662f\u8ba8\u8bba\u4e86\u7c7b\u578b\u68c0\u67e5\u5668\uff0c\u4f46\u662f\u8fd8\u4e00\u76f4\u6ca1\u6709\u7528\u8fc7\u3002\u73b0\u5728\u8ba9\u6211\u4eec\u4e86\u89e3\u4e0b\u6211\u4eec\u7684\u65b0\u670b\u53cb <code class=\"notranslate\">tsc<\/code> \u2014\u2014 TypeScript \u7f16\u8bd1\u5668\u3002\u9996\u5148\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7 npm \u5b89\u88c5\u5b83\uff1a<\/p>\n<div class=\"highlight highlight-source-shell notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"npm install -g typescript\">\n<pre class=\"notranslate\">npm install -g typescript<\/pre>\n<\/div>\n<blockquote>\n<p dir=\"auto\">\u8fd9\u4f1a\u628a TypeScript \u7f16\u8bd1\u5668\u5b89\u88c5\u5728\u5168\u5c40\uff0c\u5982\u679c\u4f60\u60f3\u628a <code class=\"notranslate\">tsc<\/code> \u5b89\u88c5\u5728\u4e00\u4e2a\u672c\u5730\u7684 <code class=\"notranslate\">node_modules<\/code> \u4e2d\uff0c\u4f60\u4e5f\u53ef\u4ee5\u4f7f\u7528 npx \u6216\u8005\u7c7b\u4f3c\u7684\u5de5\u5177\u3002<\/p>\n<\/blockquote>\n<p dir=\"auto\">\u8ba9\u6211\u4eec\u521b\u5efa\u4e00\u4e2a\u7a7a\u6587\u4ef6\u5939\uff0c\u7136\u540e\u5199\u4e0b\u6211\u4eec\u7b2c\u4e00\u4e2a TypeScript \u7a0b\u5e8f: <code class=\"notranslate\">hello.ts<\/code>\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='\/\/ Greets the world.\nconsole.log(\"Hello world!\");'><\/p>\n<pre class=\"notranslate\"><span class=\"pl-c\">\/\/ Greets the world.<\/span>\n<span class=\"pl-smi\">console<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">log<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">\"Hello world!\"<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u6ce8\u610f\u8fd9\u91cc\u5e76\u6ca1\u6709\u4ec0\u4e48\u591a\u4f59\u7684\u4fee\u9970\uff0c\u8fd9\u4e2a <code class=\"notranslate\">hello world<\/code> \u9879\u76ee\u5c31\u8ddf\u4f60\u7528 JavaScript \u5199\u662f\u4e00\u6837\u7684\u3002\u73b0\u5728\u4f60\u53ef\u4ee5\u8fd0\u884c <code class=\"notranslate\">tsc<\/code> \u547d\u4ee4\uff0c\u6267\u884c\u7c7b\u578b\u68c0\u67e5\uff1a<\/p>\n<div class=\"highlight highlight-source-shell notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"tsc hello.ts\">\n<pre class=\"notranslate\">tsc hello.ts<\/pre>\n<\/div>\n<p dir=\"auto\">\u73b0\u5728\u6211\u4eec\u5df2\u7ecf\u8fd0\u884c\u4e86 <code class=\"notranslate\">tsc<\/code>\uff0c\u4f46\u662f\u4f60\u4f1a\u53d1\u73b0\u4ec0\u4e48\u4e5f\u6ca1\u6709\u53d1\u751f\u3002\u786e\u5b9e\u5982\u6b64\uff0c\u56e0\u4e3a\u8fd9\u91cc\u5e76\u6ca1\u6709\u4ec0\u4e48\u7c7b\u578b\u9519\u8bef\uff0c\u6240\u4ee5\u547d\u4ee4\u884c\u91cc\u4e5f\u4e0d\u4f1a\u6709\u4efb\u4f55\u8f93\u51fa\u3002<\/p>\n<p dir=\"auto\">\u4f46\u5982\u679c\u6211\u4eec\u518d\u6b21\u68c0\u67e5\u4e00\u6b21\uff0c\u6211\u4eec\u5c31\u4f1a\u53d1\u73b0\uff0c\u6211\u4eec\u5f97\u5230\u4e86\u4e00\u4e2a\u65b0\u7684\u6587\u4ef6\u3002\u67e5\u770b\u4e00\u4e0b\u5f53\u524d\u76ee\u5f55\uff0c\u6211\u4eec\u4f1a\u53d1\u73b0 <code class=\"notranslate\">hello.ts<\/code> \u540c\u7ea7\u76ee\u5f55\u4e0b\u8fd8\u6709\u4e00\u4e2a <code class=\"notranslate\">hello.js<\/code>\uff0c\u8fd9\u5c31\u662f <code class=\"notranslate\">hello.ts<\/code> \u6587\u4ef6\u7f16\u8bd1\u8f93\u51fa\u7684\u6587\u4ef6\uff0c <code class=\"notranslate\">tsc<\/code> \u4f1a\u628a ts \u6587\u4ef6\u7f16\u8bd1\u6210\u4e00\u4e2a\u7eaf JavaScript \u6587\u4ef6\u3002\u8ba9\u6211\u4eec\u67e5\u770b\u4e00\u4e0b\u7f16\u8bd1\u8f93\u51fa\u7684\u6587\u4ef6\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='\/\/ Greets the world.\nconsole.log(\"Hello world!\");'><\/p>\n<pre class=\"notranslate\"><span class=\"pl-c\">\/\/ Greets the world.<\/span>\n<span class=\"pl-smi\">console<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">log<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">\"Hello world!\"<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u56e0\u4e3a TypeScript \u5e76\u6ca1\u6709\u4ec0\u4e48\u8981\u7f16\u8bd1\u5904\u7406\u7684\u5185\u5bb9\uff0c\u6240\u4ee5\u770b\u8d77\u6765\u8ddf\u6211\u4eec\u5199\u7684\u662f\u4e00\u6837\u7684\u3002\u7f16\u8bd1\u5668\u4f1a\u5c3d\u53ef\u80fd\u8f93\u51fa\u5e72\u51c0\u7684\u4ee3\u7801\uff0c\u5c31\u50cf\u662f\u6b63\u5e38\u5f00\u53d1\u8005\u5199\u7684\u90a3\u6837\uff0c\u5f53\u7136\u8fd9\u5e76\u4e0d\u662f\u5bb9\u6613\u7684\u4e8b\u60c5\uff0c\u4f46 TypeScript \u4f1a\u575a\u6301\u8fd9\u6837\u505a\uff0c\u6bd4\u5982\u4fdd\u6301\u7f29\u8fdb\uff0c\u6ce8\u610f\u8de8\u884c\u4ee3\u7801\uff0c\u4fdd\u7559\u6ce8\u91ca\u7b49\u3002<\/p>\n<p dir=\"auto\">\u5982\u679c\u6211\u4eec\u6267\u610f\u8981\u4ea7\u751f\u4e00\u4e2a\u7c7b\u578b\u68c0\u67e5\u9519\u8bef\u5462\uff1f\u6211\u4eec\u53ef\u4ee5\u8fd9\u6837\u5199 <code class=\"notranslate\">hello.ts<\/code>:<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='\/\/ This is an industrial-grade general-purpose greeter function:\nfunction greet(person, date) {\n  console.log(`Hello ${person}, today is ${date}!`);\n}\n \ngreet(\"Brendan\");'><\/p>\n<pre class=\"notranslate\"><span class=\"pl-c\">\/\/ This is an industrial-grade general-purpose greeter function:<\/span>\n<span class=\"pl-k\">function<\/span> <span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s1\">person<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-smi\">console<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">log<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">`Hello <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">person<\/span><span class=\"pl-kos\">}<\/span><\/span>, today is <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">}<\/span><\/span>!`<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-kos\">}<\/span>\n \n<span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">\"Brendan\"<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u6b64\u65f6\u6211\u4eec\u518d\u8fd0\u884c\u4e0b <code class=\"notranslate\">tsc hello.ts<\/code> \u3002\u8fd9\u6b21\u6211\u4eec\u4f1a\u5728\u547d\u4ee4\u884c\u91cc\u5f97\u5230\u4e00\u4e2a\u9519\u8bef\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"Expected 2 arguments, but got 1.\">\n<pre class=\"notranslate\"><span class=\"pl-smi\">Expected<\/span> <span class=\"pl-c1\">2<\/span> <span class=\"pl-smi\">arguments<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-s1\">but<\/span> <span class=\"pl-s1\">got<\/span> <span class=\"pl-c1\">1.<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">TypeScript \u544a\u8bc9\u6211\u4eec\u5c11\u4f20\u4e86\u4e00\u4e2a\u53c2\u6570\u7ed9 <code class=\"notranslate\">greet<\/code> \u51fd\u6570\u3002<\/p>\n<p dir=\"auto\">\u867d\u7136\u6211\u4eec\u7f16\u5199\u7684\u662f\u6807\u51c6\u7684 JavaScript\uff0c\u4f46 TypeScript \u4f9d\u7136\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\u627e\u5230\u4ee3\u7801\u4e2d\u7684\u9519\u8bef\uff0ccool~\u3002<\/p>\n<h2 dir=\"auto\">\u62a5\u9519\u65f6\u4ecd\u4ea7\u51fa\u6587\u4ef6\uff08Emitting with Errors\uff09<\/h2>\n<p dir=\"auto\">\u5728\u521a\u624d\u7684\u4f8b\u5b50\u4e2d\uff0c\u6709\u4e00\u4e2a\u7ec6\u8282\u4f60\u53ef\u80fd\u6ca1\u6709\u6ce8\u610f\u5230\uff0c\u90a3\u5c31\u662f\u5982\u679c\u6211\u4eec\u6253\u5f00\u7f16\u8bd1\u8f93\u51fa\u7684\u6587\u4ef6\uff0c\u6211\u4eec\u4f1a\u53d1\u73b0\u6587\u4ef6\u4f9d\u7136\u53d1\u751f\u4e86\u6539\u52a8\u3002\u8fd9\u662f\u4e0d\u662f\u6709\u70b9\u5947\u602a\uff1f<code class=\"notranslate\">tsc<\/code>  \u660e\u660e\u5df2\u7ecf\u62a5\u9519\u4e86\uff0c\u4e3a\u4ec0\u4e48\u8fd8\u8981\u518d\u7f16\u8bd1\u6587\u4ef6\uff1f\u8fd9\u5c31\u8981\u8bb2\u5230 TypeScript \u4e00\u4e2a\u6838\u5fc3\u7684\u89c2\u70b9\uff1a\u5927\u90e8\u5206\u65f6\u5019\uff0c\u4f60\u8981\u6bd4 TypeScript \u66f4\u6e05\u695a\u4f60\u7684\u4ee3\u7801\u3002<\/p>\n<p dir=\"auto\">\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u5047\u5982\u4f60\u6b63\u5728\u628a\u4f60\u7684\u4ee3\u7801\u8fc1\u79fb\u6210 TypeScript\uff0c\u8fd9\u4f1a\u4ea7\u751f\u5f88\u591a\u7c7b\u578b\u68c0\u67e5\u9519\u8bef\uff0c\u800c\u4f60\u4e0d\u5f97\u4e0d\u4e3a\u7c7b\u578b\u68c0\u67e5\u5668\u5904\u7406\u6389\u6240\u6709\u7684\u9519\u8bef\uff0c\u8fd9\u65f6\u5019\u4f60\u5c31\u8981\u60f3\u4e86\uff0c\u660e\u660e\u4e4b\u524d\u7684\u4ee3\u7801\u53ef\u4ee5\u6b63\u5e38\u5de5\u4f5c\uff0cTypeScript \u4e3a\u4ec0\u4e48\u8981\u963b\u6b62\u4ee3\u7801\u6b63\u5e38\u8fd0\u884c\u5462\uff1f<\/p>\n<p dir=\"auto\">\u6240\u4ee5 TypeScript \u5e76\u4e0d\u4f1a\u963b\u788d\u4f60\u3002\u5f53\u7136\u4e86\uff0c\u4f60\u5982\u679c\u60f3\u8981 TypeScript \u66f4\u4e25\u5389\u4e00\u4e9b\uff0c\u4f60\u53ef\u4ee5\u4f7f\u7528 <a href=\"https:\/\/www.typescriptlang.org\/tsconfig#noEmitOnError\" rel=\"nofollow\">noEmitOnError<\/a> \u7f16\u8bd1\u9009\u9879\uff0c\u8bd5\u7740\u6539\u4e0b\u4f60\u7684 <code class=\"notranslate\">hello.ts<\/code> \u6587\u4ef6\uff0c\u7136\u540e\u8fd0\u884c <code class=\"notranslate\">tsc<\/code>:<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"tsc --noEmitOnError hello.ts\">\n<pre class=\"notranslate\"><span class=\"pl-s1\">tsc<\/span> <span class=\"pl-c1\">--<\/span><span class=\"pl-s1\">noEmitOnError<\/span> <span class=\"pl-s1\">hello<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-c1\">ts<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u4f60\u4f1a\u53d1\u73b0 <code class=\"notranslate\">hello.js<\/code> \u5e76\u4e0d\u4f1a\u5f97\u5230\u66f4\u65b0\u3002<\/p>\n<h2 dir=\"auto\">\u663e\u793a\u7c7b\u578b\uff08Explicit Types\uff09<\/h2>\n<p dir=\"auto\">\u76f4\u5230\u73b0\u5728\uff0c\u6211\u4eec\u8fd8\u6ca1\u6709\u544a\u8bc9 TypeScript\uff0c<code class=\"notranslate\">person<\/code> \u548c <code class=\"notranslate\">date<\/code> \u662f\u4ec0\u4e48\u7c7b\u578b\uff0c\u8ba9\u6211\u4eec\u7f16\u8f91\u4e00\u4e0b\u4ee3\u7801\uff0c\u544a\u8bc9 TypeScript\uff0c<code class=\"notranslate\">person<\/code> \u662f\u4e00\u4e2a <code class=\"notranslate\">string<\/code> \u7c7b\u578b\uff0c<code class=\"notranslate\">date<\/code> \u662f\u4e00\u4e2a <code class=\"notranslate\">Date<\/code> \u5bf9\u8c61\u3002\u540c\u65f6\u6211\u4eec\u4f7f\u7528 <code class=\"notranslate\">date<\/code> \u7684 <code class=\"notranslate\">toDateString()<\/code> \u65b9\u6cd5\u3002<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"function greet(person: string, date: Date) {\n  console.log(`Hello ${person}, today is ${date.toDateString()}!`);\n}\"><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">function<\/span> <span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s1\">person<\/span>: <span class=\"pl-smi\">string<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-s1\">date<\/span>: <span class=\"pl-smi\">Date<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-smi\">console<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">log<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">`Hello <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">person<\/span><span class=\"pl-kos\">}<\/span><\/span>, today is <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toDateString<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">}<\/span><\/span>!`<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-kos\">}<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u6211\u4eec\u6240\u505a\u7684\u5c31\u662f\u7ed9 <code class=\"notranslate\">person<\/code> \u548c <code class=\"notranslate\">date<\/code> \u6dfb\u52a0\u4e86<strong>\u7c7b\u578b\u6ce8\u89e3\uff08type annotations\uff09<\/strong>\uff0c\u63cf\u8ff0 <code class=\"notranslate\">greet<\/code> \u51fd\u6570\u53ef\u4ee5\u652f\u6301\u4f20\u5165\u4ec0\u4e48\u6837\u7684\u503c\u3002\u4f60\u53ef\u4ee5\u5982\u6b64\u7406\u89e3\u8fd9\u4e2a<strong>\u7b7e\u540d (signature)<\/strong>\uff1a <code class=\"notranslate\">greet<\/code> \u652f\u6301\u4f20\u5165\u4e00\u4e2a <code class=\"notranslate\">string<\/code> \u7c7b\u578b\u7684 <code class=\"notranslate\">person<\/code> \u548c\u4e00\u4e2a <code class=\"notranslate\">Date<\/code> \u7c7b\u578b\u7684 <code class=\"notranslate\">date<\/code> \u3002<\/p>\n<p dir=\"auto\">\u6dfb\u52a0\u7c7b\u578b\u6ce8\u89e3\u540e\uff0cTypeScript \u5c31\u53ef\u4ee5\u63d0\u793a\u6211\u4eec\uff0c\u6bd4\u5982\u8bf4\u5f53 <code class=\"notranslate\">greet<\/code> \u88ab\u9519\u8bef\u8c03\u7528\u65f6\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"function greet(person: string, date: Date) {\n  console.log(`Hello ${person}, today is ${date.toDateString()}!`);\n}\n \ngreet(&quot;Maddison&quot;, Date());\n\/\/ Argument of type 'string' is not assignable to parameter of type 'Date'.\"><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">function<\/span> <span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s1\">person<\/span>: <span class=\"pl-smi\">string<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-s1\">date<\/span>: <span class=\"pl-smi\">Date<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-smi\">console<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">log<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">`Hello <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">person<\/span><span class=\"pl-kos\">}<\/span><\/span>, today is <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toDateString<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">}<\/span><\/span>!`<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-kos\">}<\/span>\n \n<span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">\"Maddison\"<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-smi\">Date<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-c\">\/\/ Argument of type 'string' is not assignable to parameter of type 'Date'.<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">TypeScript \u63d0\u793a\u7b2c\u4e8c\u4e2a\u53c2\u6570\u6709\u9519\u8bef\uff0c\u8fd9\u662f\u4e3a\u4ec0\u4e48\u5462\uff1f<\/p>\n<p dir=\"auto\">\u8fd9\u662f\u56e0\u4e3a\uff0c\u5728 JavaScript \u4e2d\u8c03\u7528 <code class=\"notranslate\">Date()<\/code> \u4f1a\u8fd4\u56de\u4e00\u4e2a <code class=\"notranslate\">string<\/code> \u3002\u4f7f\u7528 <code class=\"notranslate\">new Date()<\/code> \u624d\u4f1a\u4ea7\u751f <code class=\"notranslate\">Date<\/code> \u7c7b\u578b\u7684\u503c\u3002<\/p>\n<p dir=\"auto\">\u6211\u4eec\u5feb\u901f\u4fee\u590d\u4e0b\u8fd9\u4e2a\u95ee\u9898\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='function greet(person: string, date: Date) {\n  console.log(`Hello ${person}, today is ${date.toDateString()}!`);\n}\n \ngreet(\"Maddison\", new Date());'><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">function<\/span> <span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s1\">person<\/span>: <span class=\"pl-smi\">string<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-s1\">date<\/span>: <span class=\"pl-smi\">Date<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-smi\">console<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">log<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">`Hello <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">person<\/span><span class=\"pl-kos\">}<\/span><\/span>, today is <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toDateString<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">}<\/span><\/span>!`<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-kos\">}<\/span>\n \n<span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">\"Maddison\"<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-k\">new<\/span> <span class=\"pl-smi\">Date<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u8bb0\u4f4f\uff0c\u6211\u4eec\u5e76\u4e0d\u9700\u8981\u603b\u662f\u5199\u7c7b\u578b\u6ce8\u89e3\uff0c\u5927\u90e8\u5206\u65f6\u5019\uff0cTypeScript \u53ef\u4ee5\u81ea\u52a8\u63a8\u65ad\u51fa\u7c7b\u578b\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='let msg = \"hello there!\";\n\/\/ let msg: string'><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">let<\/span> <span class=\"pl-s1\">msg<\/span> <span class=\"pl-c1\">=<\/span> <span class=\"pl-s\">\"hello there!\"<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-c\">\/\/ let msg: string<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u5c3d\u7ba1\u6211\u4eec\u5e76\u6ca1\u6709\u544a\u8bc9 TypeScript\uff0c <code class=\"notranslate\">msg<\/code>  \u662f <code class=\"notranslate\">string<\/code> \u7c7b\u578b\u7684\u503c\uff0c\u4f46\u5b83\u4f9d\u7136\u63a8\u65ad\u51fa\u4e86\u7c7b\u578b\u3002\u8fd9\u662f\u4e00\u4e2a\u7279\u6027\uff0c\u5982\u679c\u7c7b\u578b\u7cfb\u7edf\u53ef\u4ee5\u6b63\u786e\u7684\u63a8\u65ad\u51fa\u7c7b\u578b\uff0c\u6700\u597d\u5c31\u4e0d\u8981\u624b\u52a8\u6dfb\u52a0\u7c7b\u578b\u6ce8\u89e3\u4e86\u3002<\/p>\n<h2 dir=\"auto\">\u7c7b\u578b\u62b9\u9664\uff08Erased Types\uff09<\/h2>\n<p dir=\"auto\">\u4e0a\u4e00\u4e2a\u4f8b\u5b50\u91cc\u7684\u4ee3\u7801\uff0cTypeScript \u4f1a\u7f16\u8bd1\u6210\u4ec0\u4e48\u6837\u5462\uff1f\u6211\u4eec\u6765\u770b\u4e00\u4e0b\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='\"use strict\";\nfunction greet(person, date) {\n    console.log(\"Hello \" + person + \", today is \" + date.toDateString() + \"!\");\n}\ngreet(\"Maddison\", new Date());'><\/p>\n<pre class=\"notranslate\"><span class=\"pl-s\">\"use strict\"<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-k\">function<\/span> <span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s1\">person<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-kos\">{<\/span>\n    <span class=\"pl-smi\">console<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">log<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">\"Hello \"<\/span> <span class=\"pl-c1\">+<\/span> <span class=\"pl-s1\">person<\/span> <span class=\"pl-c1\">+<\/span> <span class=\"pl-s\">\", today is \"<\/span> <span class=\"pl-c1\">+<\/span> <span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toDateString<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-c1\">+<\/span> <span class=\"pl-s\">\"!\"<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-kos\">}<\/span>\n<span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">\"Maddison\"<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-k\">new<\/span> <span class=\"pl-smi\">Date<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u6ce8\u610f\u4e24\u4ef6\u4e8b\u60c5\uff1a<\/p>\n<ol dir=\"auto\">\n<li>\u6211\u4eec\u7684 <code class=\"notranslate\">person<\/code>  \u548c <code class=\"notranslate\">date<\/code> \u53c2\u6570\u4e0d\u518d\u6709\u7c7b\u578b\u6ce8\u89e3<\/li>\n<li>\u6a21\u677f\u5b57\u7b26\u4e32\uff0c\u5373\u7528 &#8220;` \u5305\u88f9\u7684\u5b57\u7b26\u4e32\u88ab\u8f6c\u6362\u4e3a\u4f7f\u7528 <code class=\"notranslate\">+<\/code> \u53f7\u8fde\u63a5<\/li>\n<\/ol>\n<p dir=\"auto\">\u8ba9\u6211\u4eec\u5148\u770b\u4e0b\u7b2c\u4e00\u70b9\u3002\u7c7b\u578b\u6ce8\u89e3\u5e76\u4e0d\u662f JavaScript \u7684\u4e00\u90e8\u5206\u3002\u6240\u4ee5\u5e76\u6ca1\u6709\u4efb\u4f55\u6d4f\u89c8\u5668\u6216\u8005\u8fd0\u884c\u73af\u5883\u53ef\u4ee5\u76f4\u63a5\u8fd0\u884c TypeScript \u4ee3\u7801\u3002\u8fd9\u5c31\u662f\u4e3a\u4ec0\u4e48 TypeScript \u9700\u8981\u4e00\u4e2a\u7f16\u8bd1\u5668\uff0c\u5b83\u9700\u8981\u5c06 TypeScript \u4ee3\u7801\u8f6c\u6362\u4e3a JavaScript \u4ee3\u7801\uff0c\u7136\u540e\u4f60\u624d\u53ef\u4ee5\u8fd0\u884c\u5b83\u3002\u6240\u4ee5\u5927\u90e8\u5206 TypeScript \u72ec\u6709\u7684\u4ee3\u7801\u4f1a\u88ab\u62b9\u9664\uff0c\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u50cf\u6211\u4eec\u7684\u7c7b\u578b\u6ce8\u89e3\u5c31\u5168\u90e8\u88ab\u62b9\u9664\u4e86\u3002<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"\u8c28\u8bb0\uff1a\u7c7b\u578b\u6ce8\u89e3\u5e76\u4e0d\u4f1a\u66f4\u6539\u7a0b\u5e8f\u8fd0\u884c\u65f6\u7684\u884c\u4e3a\">\n<pre class=\"notranslate\"><span class=\"pl-s1\">\u8c28\u8bb0\uff1a\u7c7b\u578b\u6ce8\u89e3\u5e76\u4e0d\u4f1a\u66f4\u6539\u7a0b\u5e8f\u8fd0\u884c\u65f6\u7684\u884c\u4e3a<\/span><\/pre>\n<\/div>\n<h2 dir=\"auto\">\u964d\u7ea7\uff08Downleveling\uff09<\/h2>\n<p dir=\"auto\">\u6211\u4eec\u518d\u6765\u5173\u6ce8\u4e0b\u7b2c\u4e8c\u70b9\uff0c\u539f\u5148\u7684\u4ee3\u7801\u662f\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content=\"`Hello ${person}, today is ${date.toDateString()}!`;\">\n<pre class=\"notranslate\"><span class=\"pl-s\">`Hello <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">person<\/span><span class=\"pl-kos\">}<\/span><\/span>, today is <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toDateString<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">}<\/span><\/span>!`<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u88ab\u7f16\u8bd1\u6210\u4e86:<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='\"Hello \" + person + \", today is \" + date.toDateString() + \"!\";'>\n<pre class=\"notranslate\"><span class=\"pl-s\">\"Hello \"<\/span> <span class=\"pl-c1\">+<\/span> <span class=\"pl-s1\">person<\/span> <span class=\"pl-c1\">+<\/span> <span class=\"pl-s\">\", today is \"<\/span> <span class=\"pl-c1\">+<\/span> <span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toDateString<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-c1\">+<\/span> <span class=\"pl-s\">\"!\"<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<p dir=\"auto\">\u4e3a\u4ec0\u4e48\u8981\u8fd9\u6837\u505a\u5462\uff1f<\/p>\n<p dir=\"auto\">\u8fd9\u662f\u56e0\u4e3a\u6a21\u677f\u5b57\u7b26\u4e32\u662f ECMAScript2015\uff08\u4e5f\u88ab\u53eb\u505a ECMAScript 6 ,ES2015, ES6 \u7b49\uff09\u91cc\u7684\u529f\u80fd\uff0cTypeScript \u53ef\u5c06\u65b0\u7248\u672c\u7684\u4ee3\u7801\u7f16\u8bd1\u4e3a\u8001\u7248\u672c\u7684\u4ee3\u7801\uff0c\u6bd4\u5982 ECMAScript3 \u6216\u8005 ECMAScript5 \u3002\u8fd9\u4e2a\u5c06\u9ad8\u7248\u672c\u7684 ECMAScript \u8bed\u6cd5\u8f6c\u4e3a\u4f4e\u7248\u672c\u7684\u8fc7\u7a0b\u5c31\u53eb\u505a<strong>\u964d\u7ea7\uff08downleveling\uff09<\/strong> \u3002<\/p>\n<p dir=\"auto\">TypeScript \u9ed8\u8ba4\u8f6c\u6362\u4e3a <code class=\"notranslate\">ES3<\/code>\uff0c\u4e00\u4e2a ECMAScript \u975e\u5e38\u8001\u7684\u7248\u672c\u3002\u6211\u4eec\u4e5f\u53ef\u4ee5\u4f7f\u7528 <a href=\"https:\/\/www.typescriptlang.org\/tsconfig#target\" rel=\"nofollow\">target<\/a> \u9009\u9879\u8f6c\u6362\u4e3a\u6bd4\u8f83\u65b0\u7684\u4e00\u4e9b\u7248\u672c\uff0c\u6bd4\u5982\u6267\u884c <code class=\"notranslate\">--target es2015<\/code> \u4f1a\u8f6c\u6362\u4e3a ECMAScript 2015, \u8fd9\u610f\u5473\u7740\u8f6c\u6362\u540e\u7684\u4ee3\u7801\u53ef\u4ee5\u5728\u4efb\u4f55\u652f\u6301 ECMAScript 2015 \u7684\u5730\u65b9\u8fd0\u884c\u3002<\/p>\n<p dir=\"auto\">\u6267\u884c  <code class=\"notranslate\">tsc --target es2015 hello.ts<\/code> \uff0c\u8ba9\u6211\u4eec\u770b\u4e0b\u7f16\u8bd1\u6210 ES2015 \u540e\u7684\u4ee3\u7801\uff1a<\/p>\n<div class=\"highlight highlight-source-ts notranslate position-relative overflow-auto\" dir=\"auto\" data-snippet-clipboard-copy-content='function greet(person, date) {\n  console.log(`Hello ${person}, today is ${date.toDateString()}!`);\n}\ngreet(\"Maddison\", new Date());'><\/p>\n<pre class=\"notranslate\"><span class=\"pl-k\">function<\/span> <span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s1\">person<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">)<\/span> <span class=\"pl-kos\">{<\/span>\n  <span class=\"pl-smi\">console<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">log<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">`Hello <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">person<\/span><span class=\"pl-kos\">}<\/span><\/span>, today is <span class=\"pl-s1\"><span class=\"pl-kos\">${<\/span><span class=\"pl-s1\">date<\/span><span class=\"pl-kos\">.<\/span><span class=\"pl-en\">toDateString<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">}<\/span><\/span>!`<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span>\n<span class=\"pl-kos\">}<\/span>\n<span class=\"pl-en\">greet<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-s\">\"Maddison\"<\/span><span class=\"pl-kos\">,<\/span> <span class=\"pl-k\">new<\/span> <span class=\"pl-smi\">Date<\/span><span class=\"pl-kos\">(<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">)<\/span><span class=\"pl-kos\">;<\/span><\/pre>\n<\/div>\n<blockquote>\n<p dir=\"auto\">\u5c3d\u7ba1\u9ed8\u8ba4\u7684\u76ee\u6807\u662f ES3 \u7248\u672c\uff0c\u4f46\u662f\u5927\u591a\u6570\u7684\u6d4f\u89c8\u5668\u90fd\u5df2\u7ecf\u652f\u6301 ES2015 \u4e86\uff0c\u56e0\u6b64\u5927\u90e8\u5206\u5f00\u53d1\u8005\u53ef\u4ee5\u5b89\u5168\u7684\u6307\u5b9a\u4e3a ES2015 \u6216\u8005\u66f4\u65b0\u7684\u7248\u672c\uff0c\u9664\u975e\u4f60\u975e\u8981\u517c\u5bb9\u67d0\u4e2a\u95ee\u9898\u6d4f\u89c8\u5668\u3002<\/p>\n<\/blockquote>\n<h2 dir=\"auto\">\u4e25\u683c\u6a21\u5f0f\uff08Strictness\uff09<\/h2>\n<p dir=\"auto\">\u4e0d\u540c\u7684\u7528\u6237\u4f7f\u7528 TypeScript \u4f1a\u5173\u6ce8\u4e0d\u540c\u7684\u4e8b\u60c5\u3002\u4e00\u4e9b\u7528\u6237\u4f1a\u5bfb\u627e\u8f83\u4e3a\u5bbd\u677e\u7684\u4f53\u9a8c\uff0c\u65e2\u53ef\u4ee5\u5e2e\u52a9\u68c0\u67e5\u4ed6\u4eec\u7a0b\u5e8f\u4e2d\u7684\u90e8\u5206\u4ee3\u7801\uff0c\u4e5f\u53ef\u4ee5\u4eab\u53d7 TypeScript \u7684\u5de5\u5177\u529f\u80fd\u3002\u8fd9\u5c31\u662f TypeScript \u9ed8\u8ba4\u7684\u5f00\u53d1\u4f53\u9a8c\uff0c\u7c7b\u578b\u662f\u53ef\u9009\u7684\uff0c\u63a8\u65ad\u4f1a\u517c\u5bb9\u5927\u90e8\u5206\u7684\u7c7b\u578b\uff0c\u5bf9\u6709\u53ef\u80fd\u662f <code class=\"notranslate\">null<\/code>\/ <code class=\"notranslate\">undefined<\/code> \u503c\u4e5f\u4e0d\u505a\u5f3a\u5236\u68c0\u67e5\u3002\u5c31\u50cf tsc \u5728\u7f16\u8bd1\u62a5\u9519\u65f6\u4f9d\u7136\u4f1a\u8f93\u51fa\u6587\u4ef6\uff0c\u8fd9\u4e9b\u9ed8\u8ba4\u9009\u9879\u5e76\u4e0d\u4f1a\u963b\u788d\u4f60\u7684\u5f00\u53d1\u3002\u5982\u679c\u4f60\u6b63\u5728\u8fc1\u79fb JavaScript \u4ee3\u7801\uff0c\u6700\u4e00\u5f00\u59cb\u5c31\u53ef\u4ee5\u4f7f\u7528\u8fd9\u79cd\u65b9\u5f0f\u3002<\/p>\n<p dir=\"auto\">\u4e0e\u4e4b\u5f62\u6210\u9c9c\u660e\u5bf9\u6bd4\u7684\u662f\uff0c\u8fd8\u6709\u5f88\u591a\u7528\u6237\u5e0c\u671b TypeScript \u5c3d\u53ef\u80fd\u591a\u5730\u68c0\u67e5\u4ee3\u7801\uff0c\u8fd9\u5c31\u662f\u4e3a\u4ec0\u4e48\u8fd9\u95e8\u8bed\u8a00\u4f1a\u63d0\u4f9b\u4e25\u683c\u6a21\u5f0f\u8bbe\u7f6e\u3002\u4f46\u4e0d\u540c\u4e8e\u5207\u6362\u5f00\u5173\u7684\u5f62\u5f0f\uff08\u8981\u4e48\u68c0\u67e5\u8981\u4e48\u4e0d\u68c0\u67e5\uff09\uff0cTypeScript \u63d0\u4f9b\u7684\u5f62\u5f0f\u66f4\u50cf\u662f\u4e00\u4e2a\u523b\u5ea6\u76d8\uff0c\u4f60\u8d8a\u662f\u8f6c\u52a8\u5b83\uff0cTypeScript \u5c31\u4f1a\u68c0\u67e5\u8d8a\u591a\u7684\u5185\u5bb9\u3002\u8fd9\u9700\u8981\u4e00\u70b9\u989d\u5916\u7684\u5de5\u4f5c\uff0c\u4f46\u662f\u662f\u503c\u5f97\u7684\uff0c\u5b83\u53ef\u4ee5\u5e26\u6765\u66f4\u5168\u9762\u7684\u68c0\u67e5\u548c\u66f4\u51c6\u786e\u7684\u5de5\u5177\u529f\u80fd\u3002\u5982\u679c\u53ef\u80fd\u7684\u8bdd\uff0c\u65b0\u9879\u76ee\u5e94\u8be5\u59cb\u7ec8\u5f00\u542f\u8fd9\u4e9b\u4e25\u683c\u8bbe\u7f6e\u3002<\/p>\n<p dir=\"auto\">TypeScript \u6709\u51e0\u4e2a\u4e25\u683c\u6a21\u5f0f\u8bbe\u7f6e\u7684\u5f00\u5173\u3002\u9664\u975e\u7279\u6b8a\u8bf4\u660e\uff0c\u6587\u6863\u91cc\u7684\u4f8b\u5b50\u90fd\u662f\u5728\u4e25\u683c\u6a21\u5f0f\u4e0b\u5199\u7684\u3002CLI \u91cc\u7684 <a href=\"https:\/\/www.typescriptlang.org\/tsconfig\/#strict\" rel=\"nofollow\">strict<\/a> \u914d\u7f6e\u9879\uff0c\u6216\u8005 <a href=\"https:\/\/www.typescriptlang.org\/docs\/handbook\/tsconfig-json.html\" rel=\"nofollow\">tsconfig.json<\/a> \u4e2d\u7684 <code class=\"notranslate\">\"strict\": true<\/code> \u53ef\u4ee5\u540c\u65f6\u5f00\u542f\uff0c\u4e5f\u53ef\u4ee5\u5206\u5f00\u8bbe\u7f6e\u3002\u5728\u8fd9\u4e9b\u8bbe\u7f6e\u91cc\uff0c\u4f60\u6700\u9700\u8981\u4e86\u89e3\u7684\u662f <a href=\"https:\/\/www.typescriptlang.org\/tsconfig#noImplicitAny\" rel=\"nofollow\">noImplicitAny<\/a> \u548c <a href=\"https:\/\/www.typescriptlang.org\/tsconfig#strictNullChecks\" rel=\"nofollow\">strictNullChecks<\/a>\u3002<\/p>\n<h2 dir=\"auto\"><code class=\"notranslate\">noImplicitAny<\/code><\/h2>\n<p dir=\"auto\">\u5728\u67d0\u4e9b\u65f6\u5019\uff0cTypeScript \u5e76\u4e0d\u4f1a\u4e3a\u6211\u4eec\u63a8\u65ad\u7c7b\u578b\uff0c\u8fd9\u65f6\u5019\u5c31\u4f1a\u56de\u9000\u5230\u6700\u5bbd\u6cdb\u7684\u7c7b\u578b\uff1a<code class=\"notranslate\">any<\/code> \u3002\u8fd9\u5012\u4e0d\u662f\u6700\u7cdf\u7cd5\u7684\u4e8b\u60c5\uff0c\u6bd5\u7adf\u56de\u9000\u5230 <code class=\"notranslate\">any<\/code>\u5c31\u8ddf\u6211\u4eec\u5199 JavaScript \u6ca1\u5565\u4e00\u6837\u4e86\u3002<\/p>\n<p dir=\"auto\">\u4f46\u662f\uff0c\u7ecf\u5e38\u4f7f\u7528 <code class=\"notranslate\">any<\/code> \u6709\u8fdd\u80cc\u6211\u4eec\u4f7f\u7528 TypeScript \u7684\u76ee\u7684\u3002\u4f60\u7a0b\u5e8f\u4f7f\u7528\u7684\u7c7b\u578b\u8d8a\u591a\uff0c\u4f60\u5728\u9a8c\u8bc1\u548c\u5de5\u5177\u4e0a\u5f97\u5230\u7684\u5e2e\u52a9\u5c31\u4f1a\u8d8a\u591a\uff0c\u8fd9\u4e5f\u610f\u5473\u7740\u5199\u4ee3\u7801\u7684\u65f6\u5019\u4f1a\u9047\u5230\u66f4\u5c11\u7684 bug\u3002\u542f\u7528 <a href=\"https:\/\/www.typescriptlang.org\/tsconfig#noImplicitAny\" rel=\"nofollow\">noImplicitAny<\/a> \u914d\u7f6e\u9879\u540e\uff0c\u5f53\u7c7b\u578b\u88ab\u9690\u5f0f\u63a8\u65ad\u4e3a <code class=\"notranslate\">any<\/code> \u65f6\uff0c\u4f1a\u629b\u51fa\u4e00\u4e2a\u9519\u8bef\u3002<\/p>\n<h2 dir=\"auto\"><code class=\"notranslate\">strictNullChecks<\/code><\/h2>\n<p dir=\"auto\">\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c\u50cf <code class=\"notranslate\">null<\/code> \u548c <code class=\"notranslate\">undefined<\/code> \u8fd9\u6837\u7684\u503c\u53ef\u4ee5\u8d4b\u503c\u7ed9\u5176\u4ed6\u7684\u7c7b\u578b\u3002\u8fd9\u53ef\u4ee5\u8ba9\u6211\u4eec\u66f4\u65b9\u4fbf\u7684\u5199\u4e00\u4e9b\u4ee3\u7801\u3002\u4f46\u662f\u5fd8\u8bb0\u5904\u7406 <code class=\"notranslate\">null<\/code>  \u548c <code class=\"notranslate\">undefined<\/code> \u4e5f\u5bfc\u81f4\u4e86\u4e0d\u5c11\u7684 bug\uff0c\u751a\u81f3\u6709\u4e9b\u4eba\u4f1a\u79f0\u547c\u5b83\u4e3a<a href=\"https:\/\/www.youtube.com\/watch?v=ybrQvs4x0Ps\" rel=\"nofollow\">\u4ef7\u503c\u767e\u4e07\u7684\u9519\u8bef<\/a>\uff01  <a href=\"https:\/\/www.typescriptlang.org\/tsconfig#strictNullChecks\" rel=\"nofollow\">strictNullChecks<\/a> \u9009\u9879\u4f1a\u8ba9\u6211\u4eec\u66f4\u660e\u786e\u7684\u5904\u7406 <code class=\"notranslate\">null<\/code> \u548c <code class=\"notranslate\">undefined<\/code>\uff0c\u4e5f\u4f1a\u8ba9\u6211\u4eec\u514d\u4e8e\u5fe7\u8651\u662f\u5426\u5fd8\u8bb0\u5904\u7406 <code class=\"notranslate\">null<\/code> \u548c <code class=\"notranslate\">undefined<\/code> \u3002<\/p>\n<h2 dir=\"auto\">TypeScript \u7cfb\u5217<\/h2>\n<p dir=\"auto\">TypeScript \u7cfb\u5217\u6587\u7ae0\u7531\u5b98\u65b9\u6587\u6863\u7ffb\u8bd1\u3001\u91cd\u96be\u70b9\u89e3\u6790\u3001\u5b9e\u6218\u6280\u5de7\u4e09\u4e2a\u90e8\u5206\u7ec4\u6210\uff0c\u6db5\u76d6\u5165\u95e8\u3001\u8fdb\u9636\u3001\u5b9e\u6218\uff0c\u65e8\u5728\u4e3a\u4f60\u63d0\u4f9b\u4e00\u4e2a\u7cfb\u7edf\u5b66\u4e60 TS \u7684\u6559\u7a0b\uff0c\u5168\u7cfb\u5217\u9884\u8ba1 40 \u7bc7\u5de6\u53f3\u3002<a href=\"http:\/\/ts.yayujs.com\/\" rel=\"nofollow\">\u70b9\u6b64\u6d4f\u89c8\u5168\u7cfb\u5217\u6587\u7ae0\uff0c\u5e76\u5efa\u8bae\u987a\u4fbf\u6536\u85cf\u7ad9\u70b9\u3002<\/a><\/p>\n<p dir=\"auto\">\u5fae\u4fe1\uff1a\u300cmqyqingfeng\u300d\uff0c\u52a0\u6211\u8fdb\u51b4\u7fbd\u552f\u4e00\u7684\u8bfb\u8005\u7fa4\u3002<\/p>\n<\/td>\n<p>\u6587\u7ae0\u8f6c\u8f7d\u81ea<a href='https:\/\/github.com\/mqyqingfeng\/Blog\/issues\/227'>https:\/\/github.com\/mqyqingfeng\/Blog\/issues\/227<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u524d\u8a00 TypeScript \u7684\u5b98\u65b9\u6587\u6863\u65e9\u5df2\u66f4\u65b0\uff0c\u4f46\u6211\u80fd\u627e\u5230\u7684\u4e2d\u6587\u6587\u6863\u90fd\u8fd8\u505c\u7559\u5728\u6bd4\u8f83\u8001\u7684\u7248\u672c\u3002\u6240\u4ee5\u5bf9\u5176\u4e2d\u65b0\u589e\u4ee5\u53ca\u4fee\u8ba2\u8f83\u591a\u7684\u4e00\u4e9b\u7ae0\u8282\u8fdb\u884c\u4e86\u7ffb\u8bd1\u6574\u7406\u3002 \u672c\u7bc7\u6574\u7406\u81ea T&#8230;<\/p>\n<p class=\"read-more\"><a class=\"btn btn-default\" href=\"https:\/\/www.lccc.top\/?p=1417\"> Read More<span class=\"screen-reader-text\">  Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1417","post","type-post","status-publish","format-standard","hentry","category-learn"],"_links":{"self":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1417"}],"collection":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1417"}],"version-history":[{"count":1,"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1417\/revisions"}],"predecessor-version":[{"id":2397,"href":"https:\/\/www.lccc.top\/index.php?rest_route=\/wp\/v2\/posts\/1417\/revisions\/2397"}],"wp:attachment":[{"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1417"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1417"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lccc.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1417"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}