{"id":701,"date":"2026-02-07T00:27:57","date_gmt":"2026-02-06T16:27:57","guid":{"rendered":"https:\/\/blog.itsmygo.uk\/2026\/02\/07\/%e3%80%90typescript-%e5%85%a5%e9%96%80%e6%95%99%e5%ad%b8%e3%80%9104-union%e3%80%81literal-%e8%88%87%e5%9e%8b%e5%88%a5%e6%94%b6%e7%aa%84\/"},"modified":"2026-02-07T00:41:31","modified_gmt":"2026-02-06T16:41:31","slug":"%e3%80%90typescript-%e5%85%a5%e9%96%80%e6%95%99%e5%ad%b8%e3%80%9104-union%e3%80%81literal-%e8%88%87%e5%9e%8b%e5%88%a5%e6%94%b6%e7%aa%84","status":"publish","type":"post","link":"https:\/\/blog.itsmygo.uk\/wordpress\/2026\/02\/07\/%e3%80%90typescript-%e5%85%a5%e9%96%80%e6%95%99%e5%ad%b8%e3%80%9104-union%e3%80%81literal-%e8%88%87%e5%9e%8b%e5%88%a5%e6%94%b6%e7%aa%84\/","title":{"rendered":"\u3010TypeScript \u5165\u9580\u6559\u5b78\u3011#04 Union\u3001Literal \u8207\u578b\u5225\u6536\u7a84"},"content":{"rendered":"\n<div id=\"quiz-b5f47003\">\n<style>\n#quiz-b5f47003 .question {\n        background: white;\n        border-radius: 8px;\n        padding: 20px;\n        margin: 20px 0;\n        box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);\n      }#quiz-b5f47003 .question h3 {\n        margin-top: 0;\n        color: #333;\n      }#quiz-b5f47003 .options {\n        list-style: none;\n        padding: 0;\n      }#quiz-b5f47003 .options li {\n        padding: 12px 15px;\n        margin: 8px 0;\n        border: 2px solid #ddd;\n        border-radius: 6px;\n        cursor: pointer;\n        transition: all 0.2s;\n      }#quiz-b5f47003 .options li:hover:not(.disabled) {\n        border-color: #4caf50;\n        background: #f0fff0;\n      }#quiz-b5f47003 .options li.correct {\n        border-color: #4caf50;\n        background: #e8f5e9;\n      }#quiz-b5f47003 .options li.wrong {\n        border-color: #f44336;\n        background: #ffebee;\n      }#quiz-b5f47003 .options li.disabled {\n        cursor: default;\n        opacity: 0.7;\n      }#quiz-b5f47003 .options li.show-answer {\n        border-color: #4caf50;\n        background: #e8f5e9;\n      }#quiz-b5f47003 .feedback {\n        margin-top: 15px;\n        padding: 12px;\n        border-radius: 6px;\n        display: none;\n      }#quiz-b5f47003 .feedback.correct {\n        background: #e8f5e9;\n        color: #2e7d32;\n        display: block;\n      }#quiz-b5f47003 .feedback.wrong {\n        background: #ffebee;\n        color: #c62828;\n        display: block;\n      }#quiz-b5f47003 .score {\n        text-align: center;\n        font-size: 1.5em;\n        padding: 20px;\n        background: white;\n        border-radius: 8px;\n        margin-top: 20px;\n      }#quiz-b5f47003 .code-block {\n        background: #1e1e1e;\n        color: #d4d4d4;\n        padding: 14px;\n        border-radius: 6px;\n        font-family: \"Monaco\", \"Consolas\", \"Courier New\", monospace;\n        font-size: 0.9em;\n        overflow-x: auto;\n        margin: 12px 0;\n        white-space: pre-wrap;\n      }\n<\/style>\n<h1>\u6e2c\u9a57\uff1aUnion\u3001Literal \u8207\u578b\u5225\u6536\u7a84<\/h1>\n    <p>\u5171 5 \u984c\uff0c\u9ede\u9078\u7b54\u6848\u5f8c\u6703\u7acb\u5373\u986f\u793a\u7d50\u679c<\/p>\n\n    <div class=\"question\" id=\"q1\">\n      <h3>1. \u5728 TypeScript \u4e2d\uff0c<code>string | number<\/code> \u7684 <code>|<\/code> \u4ee3\u8868\u4ec0\u9ebc\u610f\u601d\uff1f<\/h3>\n      <ul class=\"options\">\n        <li onclick=\"checkAnswer(1, 'A', 'B')\">A. \u9019\u500b\u8b8a\u6578\u540c\u6642\u662f string \u548c number<\/li>\n        <li onclick=\"checkAnswer(1, 'B', 'B')\">B. \u9019\u500b\u8b8a\u6578\u53ef\u4ee5\u662f string \u6216 number<\/li>\n        <li onclick=\"checkAnswer(1, 'C', 'B')\">C. \u9019\u500b\u8b8a\u6578\u6703\u5148\u662f string\uff0c\u4e4b\u5f8c\u8b8a\u6210 number<\/li>\n        <li onclick=\"checkAnswer(1, 'D', 'B')\">D. \u9019\u662f\u4f4d\u5143\u904b\u7b97\uff0c\u6703\u628a string \u548c number \u505a OR \u904b\u7b97<\/li>\n      <\/ul>\n      <div class=\"feedback\" id=\"fb1\"><\/div>\n    <\/div>\n\n    <div class=\"question\" id=\"q2\">\n      <h3>2. \u4ee5\u4e0b\u7a0b\u5f0f\u78bc\u4e2d\uff0c<code>type Status = \"loading\" | \"success\" | \"error\"<\/code> \u5c6c\u65bc\u4ec0\u9ebc\u578b\u5225\uff1f<\/h3>\n      <ul class=\"options\">\n        <li onclick=\"checkAnswer(2, 'A', 'C')\">A. Union \u578b\u5225\uff0c\u5141\u8a31\u4efb\u4f55\u5b57\u4e32\u503c<\/li>\n        <li onclick=\"checkAnswer(2, 'B', 'C')\">B. typeof \u6536\u7a84\uff0c\u7528\u4f86\u6aa2\u67e5\u578b\u5225<\/li>\n        <li onclick=\"checkAnswer(2, 'C', 'C')\">C. Literal \u578b\u5225\uff0c\u53ea\u80fd\u662f\u9019\u4e09\u500b\u7279\u5b9a\u5b57\u4e32\u4e4b\u4e00<\/li>\n        <li onclick=\"checkAnswer(2, 'D', 'C')\">D. \u53ef\u8fa8\u8b58\u806f\u5408\uff0c\u7528\u5171\u540c\u5c6c\u6027\u5206\u8fa8\u578b\u5225<\/li>\n      <\/ul>\n      <div class=\"feedback\" id=\"fb2\"><\/div>\n    <\/div>\n\n    <div class=\"question\" id=\"q3\">\n      <h3>3. \u70ba\u4ec0\u9ebc\u4ee5\u4e0b\u7a0b\u5f0f\u78bc\u6703\u5831\u932f\uff1f<\/h3>\n      <div class=\"code-block\">function printLength(value: string | number) {\n    console.log(value.length);\n}<\/div>\n      <ul class=\"options\">\n        <li onclick=\"checkAnswer(3, 'A', 'D')\">A. string \u6c92\u6709 .length \u5c6c\u6027<\/li>\n        <li onclick=\"checkAnswer(3, 'B', 'D')\">B. \u4e0d\u80fd\u5728\u51fd\u5f0f\u53c3\u6578\u4f7f\u7528 Union \u578b\u5225<\/li>\n        <li onclick=\"checkAnswer(3, 'C', 'D')\">C. console.log \u4e0d\u652f\u63f4\u63a5\u6536 .length \u7684\u7d50\u679c<\/li>\n        <li onclick=\"checkAnswer(3, 'D', 'D')\">D. number \u6c92\u6709 .length \u5c6c\u6027\uff0cTypeScript \u4e0d\u78ba\u5b9a value \u662f\u54ea\u7a2e\u578b\u5225\u6240\u4ee5\u4e0d\u5141\u8a31<\/li>\n      <\/ul>\n      <div class=\"feedback\" id=\"fb3\"><\/div>\n    <\/div>\n\n    <div class=\"question\" id=\"q4\">\n      <h3>4. \u770b\u4ee5\u4e0b\u7a0b\u5f0f\u78bc\uff0cTypeScript \u5982\u4f55\u5224\u65b7 <code>animal<\/code> \u662f Fish \u9084\u662f Bird\uff1f<\/h3>\n      <div class=\"code-block\">type Fish = { swim: () => void };\ntype Bird = { fly: () => void };\n\nfunction move(animal: Fish | Bird) {\n    if (&#8220;swim&#8221; in animal) {\n        animal.swim();\n    } else {\n        animal.fly();\n    }\n}<\/div>\n      <ul class=\"options\">\n        <li onclick=\"checkAnswer(4, 'A', 'B')\">A. \u7528 typeof \u6aa2\u67e5 animal \u7684\u57fa\u672c\u578b\u5225<\/li>\n        <li onclick=\"checkAnswer(4, 'B', 'B')\">B. \u7528 in \u6aa2\u67e5\u7269\u4ef6\u6709\u6c92\u6709 &#8220;swim&#8221; \u5c6c\u6027\uff0c\u6709\u7684\u8a71\u5c31\u77e5\u9053\u662f Fish<\/li>\n        <li onclick=\"checkAnswer(4, 'C', 'B')\">C. \u7528 instanceof \u6aa2\u67e5 animal \u662f\u5426\u70ba Fish \u7684\u5be6\u4f8b<\/li>\n        <li onclick=\"checkAnswer(4, 'D', 'B')\">D. \u7528\u53ef\u8fa8\u8b58\u806f\u5408\uff0c\u900f\u904e\u5171\u540c\u7684 type \u5c6c\u6027\u4f86\u5206\u8fa8<\/li>\n      <\/ul>\n      <div class=\"feedback\" id=\"fb4\"><\/div>\n    <\/div>\n\n    <div class=\"question\" id=\"q5\">\n      <h3>5. \u4ee5\u4e0b\u7a0b\u5f0f\u78bc\u4e2d\uff0c<code>user?.name ?? \"\u533f\u540d\"<\/code> \u7684\u5b8c\u6574\u610f\u601d\u662f\u4ec0\u9ebc\uff1f<\/h3>\n      <div class=\"code-block\">const name = user?.name ?? &#8220;\u533f\u540d&#8221;;<\/div>\n      <ul class=\"options\">\n        <li onclick=\"checkAnswer(5, 'A', 'C')\">A. \u5982\u679c user.name \u662f\u7a7a\u5b57\u4e32\uff0c\u5c31\u7528 &#8220;\u533f\u540d&#8221;<\/li>\n        <li onclick=\"checkAnswer(5, 'B', 'C')\">B. \u4fdd\u8b49 user \u4e0d\u662f null\uff0c\u7136\u5f8c\u53d6\u5f97 name<\/li>\n        <li onclick=\"checkAnswer(5, 'C', 'C')\">C. \u5982\u679c user \u662f null\/undefined \u5c31\u56de\u50b3 undefined\uff0c\u518d\u7528 ?? \u5728 null\/undefined \u6642\u6539\u7528 &#8220;\u533f\u540d&#8221;<\/li>\n        <li onclick=\"checkAnswer(5, 'D', 'C')\">D. \u5148\u65b7\u8a00 user \u5b58\u5728\uff0c\u5982\u679c name \u662f falsy \u503c\u5c31\u7528 &#8220;\u533f\u540d&#8221;<\/li>\n      <\/ul>\n      <div class=\"feedback\" id=\"fb5\"><\/div>\n    <\/div>\n\n    <div class=\"score\" id=\"score\" style=\"display:none;\"><\/div>\n<script>\n\n      let answered = 0;\n      let correct = 0;\n      const total = 5;\n      const explanations = {\n        1: \" Union \u578b\u5225\u4e2d\u7684 <code>|<\/code> \u5ff5\u4f5c\u300c\u6216\u300d\uff0c\u4ee3\u8868\u8b8a\u6578\u53ef\u4ee5\u662f\u5176\u4e2d\u4efb\u4e00\u7a2e\u578b\u5225\u3002<code>string | number<\/code> \u5c31\u662f\u300c\u53ef\u4ee5\u662f\u6587\u5b57\u6216\u6578\u5b57\u300d\uff0c\u800c\u4e0d\u662f\u540c\u6642\u5169\u8005\u3002\",\n        2: \" Literal \u578b\u5225\u662f\u628a\u5141\u8a31\u7684\u503c\u4e00\u500b\u4e00\u500b\u5217\u51fa\u4f86\u3002<code>\\\"loading\\\" | \\\"success\\\" | \\\"error\\\"<\/code> \u4ee3\u8868 Status \u53ea\u80fd\u662f\u9019\u4e09\u500b\u7279\u5b9a\u5b57\u4e32\u4e4b\u4e00\uff0c\u4e0d\u662f\u4efb\u610f\u5b57\u4e32\u90fd\u884c\u3002\u96d6\u7136\u8a9e\u6cd5\u4e0a\u4e5f\u7528\u5230 <code>|<\/code>\uff08Union\uff09\uff0c\u4f46\u56e0\u70ba\u6bcf\u500b\u503c\u90fd\u662f\u56fa\u5b9a\u7684\u5b57\u4e32\u5b57\u9762\u503c\uff0c\u6240\u4ee5\u7a31\u70ba Literal \u578b\u5225\u3002\",\n        3: \" TypeScript \u4e0d\u77e5\u9053 value \u662f string \u9084\u662f number\u3002\u56e0\u70ba number \u6c92\u6709 .length \u5c6c\u6027\uff0c\u6240\u4ee5\u5728\u9084\u6c92\u6536\u7a84\uff08narrowing\uff09\u4e4b\u524d\uff0cTypeScript \u4e0d\u8b93\u4f60\u76f4\u63a5\u7528 .length\u3002\u4f60\u9700\u8981\u5148\u7528 <code>typeof value === \\\"string\\\"<\/code> \u6aa2\u67e5\uff0c\u624d\u80fd\u5b89\u5168\u4f7f\u7528\u3002\",\n        4: \" \u9019\u88e1\u4f7f\u7528\u7684\u662f <code>in<\/code> \u6536\u7a84\u3002<code>\\\"swim\\\" in animal<\/code> \u662f\u5728\u554f\u300canimal \u9019\u500b\u7269\u4ef6\u88e1\u6709\u6c92\u6709 swim \u9019\u500b\u5c6c\u6027\u300d\u3002\u5982\u679c\u6709\uff0cTypeScript \u5c31\u63a8\u65b7\u5b83\u662f Fish \u578b\u5225\u3002typeof \u662f\u7528\u4f86\u6aa2\u67e5\u57fa\u672c\u578b\u5225\uff08string\u3001number\uff09\uff0cinstanceof \u662f\u7528\u4f86\u6aa2\u67e5 class \u5be6\u4f8b\uff0c\u90fd\u4e0d\u9069\u7528\u65bc\u9019\u500b\u60c5\u5883\u3002\",\n        5: \" <code>?.<\/code>\uff08\u53ef\u9078\u93c8\uff09\u6703\u5728 user \u70ba null \u6216 undefined \u6642\u5b89\u5168\u5730\u56de\u50b3 undefined\uff0c\u4e0d\u6703\u5831\u932f\u3002<code>??<\/code>\uff08\u7a7a\u503c\u5408\u4f75\uff09\u6703\u5728\u5de6\u908a\u7684\u503c\u70ba null \u6216 undefined \u6642\u4f7f\u7528\u53f3\u908a\u7684\u9810\u8a2d\u503c\u3002\u6240\u4ee5\u6574\u9ad4\u6548\u679c\u662f\uff1a\u5b89\u5168\u5730\u53d6 user.name\uff0c\u5982\u679c\u53d6\u4e0d\u5230\u5c31\u7528 \\\"\u533f\u540d\\\"\u3002\u6ce8\u610f <code>??<\/code> \u53ea\u91dd\u5c0d null\/undefined\uff0c\u7a7a\u5b57\u4e32\u4e0d\u6703\u89f8\u767c\u3002\"\n      };\n\n      function checkAnswer(qNum, selected, correctAns) {\n        const question = document.getElementById(\"q\" + qNum);\n        if (question.classList.contains(\"answered\")) return;\n\n        question.classList.add(\"answered\");\n        answered++;\n\n        const options = question.querySelectorAll(\".options li\");\n        options.forEach((opt) => {\n          opt.classList.add(\"disabled\");\n          if (opt.textContent.startsWith(correctAns + \".\")) {\n            opt.classList.add(\"show-answer\");\n          }\n        });\n\n        const feedback = document.getElementById(\"fb\" + qNum);\n        if (selected === correctAns) {\n          correct++;\n          feedback.className = \"feedback correct\";\n          feedback.innerHTML = \"\u2713 \u6b63\u78ba\uff01\" + explanations[qNum];\n        } else {\n          feedback.className = \"feedback wrong\";\n          feedback.innerHTML =\n            \"\u2717 \u932f\u8aa4\u3002\u6b63\u78ba\u7b54\u6848\u662f \" + correctAns + \"\u3002\" + explanations[qNum];\n          options.forEach((opt) => {\n            if (opt.textContent.startsWith(selected + \".\")) {\n              opt.classList.add(\"wrong\");\n            }\n          });\n        }\n\n        if (answered === total) {\n          const scoreDiv = document.getElementById(\"score\");\n          scoreDiv.style.display = \"block\";\n          scoreDiv.innerHTML =\n            \"\u6e2c\u9a57\u5b8c\u6210\uff01\u5f97\u5206\uff1a\" +\n            correct +\n            \" \/ \" +\n            total +\n            (correct === total\n              ? \" \ud83c\udf89 \u5168\u5c0d\uff01\"\n              : correct >= Math.ceil(total * 0.6)\n                ? \" \ud83d\udc4d \u4e0d\u932f\uff01\"\n                : \" \ud83d\udcda \u518d\u8907\u7fd2\u4e00\u4e0b\u5427\");\n        }\n      }\n    \n<\/script>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e00\u53e5\u8a71\u8aaa\u660e<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u8b93\u4e00\u500b\u8b8a\u6578\u53ef\u4ee5\u662f\u597d\u5e7e\u7a2e\u578b\u5225\uff0c\u4f46 TypeScript \u6703\u903c\u4f60\u300c\u78ba\u8a8d\u6e05\u695a\u4e86\u300d\u624d\u80fd\u7528\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u70ba\u4ec0\u9ebc\u8981\u5b78\u9019\u500b\uff1f<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u4f60\u8acb AI \u5e6b\u4f60\u5beb TypeScript \u6642\uff0c\u7522\u51fa\u7684\u7a0b\u5f0f\u78bc\u88e1\u5f88\u5e38\u51fa\u73fe <code>string | number<\/code>\u3001<code>if (typeof x === \"string\")<\/code> \u9019\u985e\u5beb\u6cd5\u3002\u9019\u4e0d\u662f AI \u5728\u641e\u82b1\u6a23 &#8212; \u9019\u662f TypeScript \u7684\u6838\u5fc3\u6a5f\u5236\u3002\u770b\u4e0d\u61c2\u9019\u4e9b\uff0c\u4f60\u5c31\u5f88\u96e3\u5224\u65b7 AI \u5beb\u7684\u7a0b\u5f0f\u78bc\u5230\u5e95\u5c0d\u4e0d\u5c0d\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">1. Union \u578b\u5225\uff1a\u300c\u53ef\u4ee5\u662f A \u6216 B\u300d<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u6700\u5c0f\u7bc4\u4f8b<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-keyword\">let<\/span> value: string | number;\nvalue = <span class=\"hljs-string\">\"hello\"<\/span>;   <span class=\"hljs-comment\">\/\/ OK<\/span>\nvalue = <span class=\"hljs-number\">42<\/span>;        <span class=\"hljs-comment\">\/\/ OK<\/span>\nvalue = <span class=\"hljs-literal\">true<\/span>;      <span class=\"hljs-comment\">\/\/ \u932f\u8aa4\uff01\u53ea\u80fd\u662f string \u6216 number<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u9010\u884c\u7ffb\u8b6f<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-2\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-keyword\">let<\/span> value: string | number;\n<span class=\"hljs-comment\">\/\/         \u2191 \u9019\u500b | \u5ff5\u4f5c\u300c\u6216\u300d<\/span>\n<span class=\"hljs-comment\">\/\/         \u610f\u601d\u662f\uff1avalue \u53ef\u4ee5\u662f\u6587\u5b57\uff0c\u4e5f\u53ef\u4ee5\u662f\u6578\u5b57<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-2\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u4e00\u53e5\u8a71<\/strong>\uff1a<code>|<\/code> \u5c31\u662f\u300c\u6216\u300d\u7684\u610f\u601d\u3002<code>string | number<\/code> \u4ee3\u8868\u300c\u53ef\u4ee5\u662f\u6587\u5b57\u6216\u6578\u5b57\u300d\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u5e38\u898b\u8b8a\u5316<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">AI \u6700\u5e38\u7522\u51fa\u7684\u5e7e\u7a2e Union \u5beb\u6cd5\uff1a<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u8b8a\u5316 1\uff1a\u5141\u8a31 null<\/h4>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-3\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-keyword\">let<\/span> user: User | <span class=\"hljs-literal\">null<\/span>;\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-3\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u7ffb\u8b6f<\/strong>\uff1auser \u53ef\u4ee5\u662f\u4e00\u500b User \u7269\u4ef6\uff0c\u4e5f\u53ef\u4ee5\u662f null\uff08\u9084\u6c92\u6709\u503c\uff09\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u8b8a\u5316 2\uff1a\u51fd\u5f0f\u7684\u53c3\u6578<\/h4>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-4\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">printId<\/span>(<span class=\"hljs-params\">id: string | number<\/span>) <\/span>{\n    <span class=\"hljs-built_in\">console<\/span>.log(id);\n}\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-4\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u7ffb\u8b6f<\/strong>\uff1aprintId \u9019\u500b\u51fd\u5f0f\u63a5\u53d7\u6587\u5b57\u6216\u6578\u5b57\u7576 id\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u8b8a\u5316 3\uff1a\u51fd\u5f0f\u7684\u56de\u50b3\u503c<\/h4>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-5\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">find<\/span>(<span class=\"hljs-params\">id: number<\/span>): <span class=\"hljs-title\">User<\/span> | <span class=\"hljs-title\">undefined<\/span> <\/span>{\n    <span class=\"hljs-comment\">\/\/ ...<\/span>\n}\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-5\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u7ffb\u8b6f<\/strong>\uff1afind \u53ef\u80fd\u56de\u50b3\u4e00\u500b User\uff0c\u4e5f\u53ef\u80fd\u56de\u50b3 undefined\uff08\u627e\u4e0d\u5230\uff09\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">2. Literal \u578b\u5225\uff1a\u300c\u53ea\u80fd\u662f\u9019\u5e7e\u500b\u7279\u5b9a\u503c\u300d<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u6700\u5c0f\u7bc4\u4f8b<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-6\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\">type Direction = <span class=\"hljs-string\">\"up\"<\/span> | <span class=\"hljs-string\">\"down\"<\/span> | <span class=\"hljs-string\">\"left\"<\/span> | <span class=\"hljs-string\">\"right\"<\/span>;\n\n<span class=\"hljs-keyword\">let<\/span> dir: Direction;\ndir = <span class=\"hljs-string\">\"up\"<\/span>;       <span class=\"hljs-comment\">\/\/ OK<\/span>\ndir = <span class=\"hljs-string\">\"diagonal\"<\/span>; <span class=\"hljs-comment\">\/\/ \u932f\u8aa4\uff01\u53ea\u80fd\u662f\u90a3\u56db\u500b\u503c\u4e4b\u4e00<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-6\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u9010\u884c\u7ffb\u8b6f<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-7\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\">type Direction = <span class=\"hljs-string\">\"up\"<\/span> | <span class=\"hljs-string\">\"down\"<\/span> | <span class=\"hljs-string\">\"left\"<\/span> | <span class=\"hljs-string\">\"right\"<\/span>;\n<span class=\"hljs-comment\">\/\/   \u2191 \u5b9a\u7fa9\u4e00\u500b\u578b\u5225\u53eb Direction<\/span>\n<span class=\"hljs-comment\">\/\/              \u2191 \u5b83\u53ea\u80fd\u662f\u9019\u56db\u500b\u5b57\u4e32\u4e4b\u4e00<\/span>\n\n<span class=\"hljs-keyword\">let<\/span> dir: Direction;\n<span class=\"hljs-comment\">\/\/       \u2191 dir \u53ea\u63a5\u53d7 \"up\"\u3001\"down\"\u3001\"left\"\u3001\"right\"<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-7\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u4e00\u53e5\u8a71<\/strong>\uff1aLiteral \u578b\u5225\u5c31\u662f\u300c\u628a\u5141\u8a31\u7684\u503c\u4e00\u500b\u4e00\u500b\u5217\u51fa\u4f86\u300d\u3002\u4e0d\u662f\u90a3\u5e7e\u500b\u503c\uff0cTypeScript \u5c31\u5831\u932f\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u5e38\u898b\u8b8a\u5316<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\">\u8b8a\u5316 1\uff1a\u72c0\u614b\u503c<\/h4>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-8\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\">type Status = <span class=\"hljs-string\">\"loading\"<\/span> | <span class=\"hljs-string\">\"success\"<\/span> | <span class=\"hljs-string\">\"error\"<\/span>;\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-8\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u7ffb\u8b6f<\/strong>\uff1a\u72c0\u614b\u53ea\u80fd\u662f\u9019\u4e09\u7a2e\u4e4b\u4e00\uff0c\u4e0d\u6703\u51fa\u73fe\u6253\u932f\u5b57\u7684\u60c5\u6cc1\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u8b8a\u5316 2\uff1a\u6578\u5b57 Literal<\/h4>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\"><span><code class=\"hljs\">type DiceRoll = 1 | 2 | 3 | 4 | 5 | 6;\n<\/code><\/span><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u7ffb\u8b6f<\/strong>\uff1a\u9ab0\u5b50\u53ea\u80fd\u662f 1 \u5230 6\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u8b8a\u5316 3\uff1a\u642d\u914d\u51fd\u5f0f\u53c3\u6578<\/h4>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-9\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">move<\/span>(<span class=\"hljs-params\">direction: <span class=\"hljs-string\">\"up\"<\/span> | <span class=\"hljs-string\">\"down\"<\/span> | <span class=\"hljs-string\">\"left\"<\/span> | <span class=\"hljs-string\">\"right\"<\/span><\/span>) <\/span>{\n    <span class=\"hljs-comment\">\/\/ ...<\/span>\n}\nmove(<span class=\"hljs-string\">\"up\"<\/span>);      <span class=\"hljs-comment\">\/\/ OK<\/span>\nmove(<span class=\"hljs-string\">\"forward\"<\/span>); <span class=\"hljs-comment\">\/\/ \u932f\u8aa4\uff01<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-9\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u7ffb\u8b6f<\/strong>\uff1amove \u53ea\u63a5\u53d7\u90a3\u56db\u500b\u65b9\u5411\u7684\u5b57\u4e32\uff0c\u5225\u7684\u4e00\u5f8b\u4e0d\u884c\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">3. \u578b\u5225\u6536\u7a84\uff08Narrowing\uff09\uff1a\u300c\u5148\u6aa2\u67e5\uff0c\u518d\u4f7f\u7528\u300d<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u9019\u662f\u6574\u7bc7\u6700\u91cd\u8981\u7684\u6982\u5ff5\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u554f\u984c\uff1aUnion \u578b\u5225\u4e0d\u80fd\u76f4\u63a5\u7528<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-10\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">printLength<\/span>(<span class=\"hljs-params\">value: string | number<\/span>) <\/span>{\n    <span class=\"hljs-built_in\">console<\/span>.log(value.length);\n    <span class=\"hljs-comment\">\/\/                \u2191 \u932f\u8aa4\uff01number \u6c92\u6709 .length<\/span>\n}\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-10\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\">TypeScript \u4e0d\u77e5\u9053 <code>value<\/code> \u662f string \u9084\u662f number\uff0c\u6240\u4ee5\u4e0d\u8b93\u4f60\u76f4\u63a5\u7528 <code>.length<\/code>\uff08\u56e0\u70ba\u6578\u5b57\u6c92\u6709 <code>.length<\/code>\uff09\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u89e3\u6cd5\uff1a\u5148\u7528 typeof \u6aa2\u67e5<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-11\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">printLength<\/span>(<span class=\"hljs-params\">value: string | number<\/span>) <\/span>{\n    <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> value === <span class=\"hljs-string\">\"string\"<\/span>) {\n        <span class=\"hljs-built_in\">console<\/span>.log(value.length);   <span class=\"hljs-comment\">\/\/ OK\uff01TypeScript \u77e5\u9053\u9019\u88e1\u662f string<\/span>\n    } <span class=\"hljs-keyword\">else<\/span> {\n        <span class=\"hljs-built_in\">console<\/span>.log(value);          <span class=\"hljs-comment\">\/\/ \u9019\u88e1 TypeScript \u77e5\u9053\u662f number<\/span>\n    }\n}\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-11\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u4e00\u53e5\u8a71<\/strong>\uff1aTypeScript \u6703\u300c\u8ddf\u8457\u4f60\u7684 if \u5224\u65b7\u8d70\u300d\u3002\u4f60\u6aa2\u67e5\u4e86\u662f string\uff0c\u5b83\u5c31\u8b93\u4f60\u7576 string \u7528\u3002\u9019\u5c31\u662f\u300c\u6536\u7a84\u300d&#8211; \u628a\u7bc4\u570d\u7e2e\u5c0f\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">4. typeof \u6536\u7a84\uff1a\u6700\u5e38\u898b\u7684\u6aa2\u67e5\u65b9\u5f0f<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u6700\u5c0f\u7bc4\u4f8b<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-12\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">process<\/span>(<span class=\"hljs-params\">input: string | number | boolean<\/span>) <\/span>{\n    <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> input === <span class=\"hljs-string\">\"string\"<\/span>) {\n        <span class=\"hljs-comment\">\/\/ \u9019\u88e1 input \u662f string<\/span>\n        <span class=\"hljs-built_in\">console<\/span>.log(input.toUpperCase());\n    } <span class=\"hljs-keyword\">else<\/span> <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> input === <span class=\"hljs-string\">\"number\"<\/span>) {\n        <span class=\"hljs-comment\">\/\/ \u9019\u88e1 input \u662f number<\/span>\n        <span class=\"hljs-built_in\">console<\/span>.log(input.toFixed(<span class=\"hljs-number\">2<\/span>));\n    } <span class=\"hljs-keyword\">else<\/span> {\n        <span class=\"hljs-comment\">\/\/ \u9019\u88e1 input \u662f boolean<\/span>\n        <span class=\"hljs-built_in\">console<\/span>.log(input ? <span class=\"hljs-string\">\"yes\"<\/span> : <span class=\"hljs-string\">\"no\"<\/span>);\n    }\n}\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-12\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u7ffb\u8b6f<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-13\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-keyword\">typeof<\/span> input === <span class=\"hljs-string\">\"string\"<\/span>   <span class=\"hljs-comment\">\/\/ input \u662f\u4e0d\u662f\u6587\u5b57\uff1f<\/span>\n<span class=\"hljs-keyword\">typeof<\/span> input === <span class=\"hljs-string\">\"number\"<\/span>   <span class=\"hljs-comment\">\/\/ input \u662f\u4e0d\u662f\u6578\u5b57\uff1f<\/span>\n<span class=\"hljs-keyword\">typeof<\/span> input === <span class=\"hljs-string\">\"boolean\"<\/span>  <span class=\"hljs-comment\">\/\/ input \u662f\u4e0d\u662f\u5e03\u6797\u503c\uff1f<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-13\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u4e00\u53e5\u8a71<\/strong>\uff1a<code>typeof<\/code> \u554f\u7684\u662f\u300c\u9019\u500b\u503c\u662f\u4ec0\u9ebc\u57fa\u672c\u578b\u5225\u300d\u3002TypeScript \u770b\u5230\u4f60\u7528\u4e86 typeof \u6aa2\u67e5\uff0c\u5c31\u81ea\u52d5\u77e5\u9053\u5728\u90a3\u500b if \u5340\u584a\u88e1\uff0c\u8b8a\u6578\u662f\u4ec0\u9ebc\u578b\u5225\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">5. in \u6536\u7a84\uff1a\u300c\u9019\u500b\u7269\u4ef6\u6709\u6c92\u6709\u67d0\u500b\u5c6c\u6027\u300d<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u6700\u5c0f\u7bc4\u4f8b<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-14\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\">type Fish = { <span class=\"hljs-attr\">swim<\/span>: <span class=\"hljs-function\"><span class=\"hljs-params\">()<\/span> =&gt;<\/span> <span class=\"hljs-keyword\">void<\/span> };\ntype Bird = { <span class=\"hljs-attr\">fly<\/span>: <span class=\"hljs-function\"><span class=\"hljs-params\">()<\/span> =&gt;<\/span> <span class=\"hljs-keyword\">void<\/span> };\n\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">move<\/span>(<span class=\"hljs-params\">animal: Fish | Bird<\/span>) <\/span>{\n    <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-string\">\"swim\"<\/span> <span class=\"hljs-keyword\">in<\/span> animal) {\n        animal.swim();    <span class=\"hljs-comment\">\/\/ TypeScript \u77e5\u9053\u9019\u662f Fish<\/span>\n    } <span class=\"hljs-keyword\">else<\/span> {\n        animal.fly();     <span class=\"hljs-comment\">\/\/ TypeScript \u77e5\u9053\u9019\u662f Bird<\/span>\n    }\n}\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-14\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u9010\u884c\u7ffb\u8b6f<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-15\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-string\">\"swim\"<\/span> <span class=\"hljs-keyword\">in<\/span> animal\n<span class=\"hljs-comment\">\/\/ \u2191 \u554f\uff1aanimal \u9019\u500b\u7269\u4ef6\u88e1\u9762\u6709\u6c92\u6709 \"swim\" \u9019\u500b\u5c6c\u6027\uff1f<\/span>\n<span class=\"hljs-comment\">\/\/ \u5982\u679c\u6709\uff0cTypeScript \u5c31\u63a8\u65b7\u5b83\u662f Fish<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-15\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u4e00\u53e5\u8a71<\/strong>\uff1a<code>\"\u5c6c\u6027\u540d\" in \u7269\u4ef6<\/code> \u5c31\u662f\u5728\u554f\u300c\u9019\u500b\u7269\u4ef6\u6709\u6c92\u6709\u9019\u500b\u5c6c\u6027\u300d\u3002\u6709\u7684\u8a71\uff0cTypeScript \u5c31\u77e5\u9053\u5b83\u662f\u54ea\u500b\u578b\u5225\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">6. instanceof \u6536\u7a84\uff1a\u300c\u9019\u500b\u662f\u4e0d\u662f\u67d0\u500b class \u7684\u5be6\u4f8b\u300d<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u6700\u5c0f\u7bc4\u4f8b<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-16\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">logDate<\/span>(<span class=\"hljs-params\">value: string | Date<\/span>) <\/span>{\n    <span class=\"hljs-keyword\">if<\/span> (value <span class=\"hljs-keyword\">instanceof<\/span> <span class=\"hljs-built_in\">Date<\/span>) {\n        <span class=\"hljs-built_in\">console<\/span>.log(value.getFullYear());  <span class=\"hljs-comment\">\/\/ TypeScript \u77e5\u9053\u662f Date<\/span>\n    } <span class=\"hljs-keyword\">else<\/span> {\n        <span class=\"hljs-built_in\">console<\/span>.log(value.toUpperCase());  <span class=\"hljs-comment\">\/\/ TypeScript \u77e5\u9053\u662f string<\/span>\n    }\n}\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-16\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u7ffb\u8b6f<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-17\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\">value <span class=\"hljs-keyword\">instanceof<\/span> <span class=\"hljs-built_in\">Date<\/span>\n<span class=\"hljs-comment\">\/\/ \u2191 \u554f\uff1avalue \u662f\u4e0d\u662f\u4e00\u500b Date \u7269\u4ef6\uff1f<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-17\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u4e00\u53e5\u8a71<\/strong>\uff1a<code>instanceof<\/code> \u7528\u4f86\u6aa2\u67e5\u300c\u662f\u4e0d\u662f\u67d0\u500b class \u88fd\u9020\u51fa\u4f86\u7684\u300d\u3002typeof \u7ba1\u57fa\u672c\u578b\u5225\uff08string\u3001number\uff09\uff0cinstanceof \u7ba1 class \u5be6\u4f8b\uff08Date\u3001Error\u3001\u81ea\u5b9a\u7fa9 class\uff09\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">7. \u53ef\u8fa8\u8b58\u806f\u5408\uff08Discriminated Unions\uff09\uff1a\u9760\u5171\u540c\u5c6c\u6027\u5206\u8fa8<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u9019\u662f AI \u7522\u51fa\u7684\u7a0b\u5f0f\u78bc\u88e1\u975e\u5e38\u5e38\u898b\u7684\u6a21\u5f0f\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u6700\u5c0f\u7bc4\u4f8b<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-18\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\">type Success = { <span class=\"hljs-attr\">status<\/span>: <span class=\"hljs-string\">\"success\"<\/span>; data: string };\ntype Failure = { <span class=\"hljs-attr\">status<\/span>: <span class=\"hljs-string\">\"error\"<\/span>; message: string };\ntype Result = Success | Failure;\n\n<span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">handle<\/span>(<span class=\"hljs-params\">result: Result<\/span>) <\/span>{\n    <span class=\"hljs-keyword\">if<\/span> (result.status === <span class=\"hljs-string\">\"success\"<\/span>) {\n        <span class=\"hljs-built_in\">console<\/span>.log(result.data);      <span class=\"hljs-comment\">\/\/ OK\uff01TypeScript \u77e5\u9053\u9019\u662f Success<\/span>\n    } <span class=\"hljs-keyword\">else<\/span> {\n        <span class=\"hljs-built_in\">console<\/span>.log(result.message);   <span class=\"hljs-comment\">\/\/ OK\uff01TypeScript \u77e5\u9053\u9019\u662f Failure<\/span>\n    }\n}\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-18\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u9010\u884c\u7ffb\u8b6f<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-19\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\">type Success = { <span class=\"hljs-attr\">status<\/span>: <span class=\"hljs-string\">\"success\"<\/span>; data: string };\n<span class=\"hljs-comment\">\/\/               \u2191 status \u56fa\u5b9a\u662f \"success\" \u9019\u500b\u5b57\u4e32\uff08Literal \u578b\u5225\uff09<\/span>\n\ntype Failure = { <span class=\"hljs-attr\">status<\/span>: <span class=\"hljs-string\">\"error\"<\/span>; message: string };\n<span class=\"hljs-comment\">\/\/               \u2191 status \u56fa\u5b9a\u662f \"error\"<\/span>\n\ntype Result = Success | Failure;\n<span class=\"hljs-comment\">\/\/            \u2191 Result \u662f Success \u6216 Failure<\/span>\n\n<span class=\"hljs-keyword\">if<\/span> (result.status === <span class=\"hljs-string\">\"success\"<\/span>) {\n<span class=\"hljs-comment\">\/\/  \u2191 \u7528\u5171\u540c\u7684 status \u5c6c\u6027\u4f86\u5206\u8fa8\u662f\u54ea\u4e00\u7a2e<\/span>\n<span class=\"hljs-comment\">\/\/    TypeScript \u770b\u5230 status \u662f \"success\"\uff0c\u5c31\u77e5\u9053\u6574\u500b\u7269\u4ef6\u662f Success \u578b\u5225<\/span>\n}\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-19\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u4e00\u53e5\u8a71<\/strong>\uff1a\u5e7e\u500b\u578b\u5225\u5171\u7528\u4e00\u500b\u5c6c\u6027\uff08\u5982 <code>status<\/code>\uff09\uff0c\u4f46\u503c\u4e0d\u540c\u3002TypeScript \u6839\u64da\u90a3\u500b\u5c6c\u6027\u7684\u503c\uff0c\u5c31\u80fd\u5224\u65b7\u662f\u54ea\u500b\u578b\u5225\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">AI \u5e38\u7528\u7684\u5834\u666f<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\">API \u56de\u61c9<\/h4>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-20\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\">type ApiResponse =\n    | { <span class=\"hljs-attr\">ok<\/span>: <span class=\"hljs-literal\">true<\/span>; data: User&#91;] }\n    | { <span class=\"hljs-attr\">ok<\/span>: <span class=\"hljs-literal\">false<\/span>; error: string };\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-20\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u7ffb\u8b6f<\/strong>\uff1aAPI \u56de\u4f86\u7684\u6771\u897f\uff0c\u4e0d\u662f\u6210\u529f\u5e36\u8cc7\u6599\uff0c\u5c31\u662f\u5931\u6557\u5e36\u932f\u8aa4\u8a0a\u606f\u3002\u7528 <code>ok<\/code> \u6b04\u4f4d\u4f86\u5206\u8fa8\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Redux Action\uff08\u72c0\u614b\u7ba1\u7406\uff09<\/h4>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-21\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\">type Action =\n    | { <span class=\"hljs-attr\">type<\/span>: <span class=\"hljs-string\">\"ADD_TODO\"<\/span>; text: string }\n    | { <span class=\"hljs-attr\">type<\/span>: <span class=\"hljs-string\">\"TOGGLE_TODO\"<\/span>; id: number }\n    | { <span class=\"hljs-attr\">type<\/span>: <span class=\"hljs-string\">\"DELETE_TODO\"<\/span>; id: number };\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-21\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>\u7ffb\u8b6f<\/strong>\uff1a\u4e09\u7a2e\u64cd\u4f5c\uff0c\u7528 <code>type<\/code> \u6b04\u4f4d\u4f86\u5206\u8fa8\u662f\u54ea\u4e00\u7a2e\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">8. null \u548c undefined \u7684\u8655\u7406<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">TypeScript \u9810\u8a2d\u4e0d\u5141\u8a31\u628a null \u6216 undefined \u585e\u7d66\u5176\u4ed6\u578b\u5225\u3002\u4f60\u5fc5\u9808\u660e\u78ba\u5ba3\u544a\u4e26\u8655\u7406\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u6700\u5c0f\u7bc4\u4f8b<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-22\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> <span class=\"hljs-title\">greet<\/span>(<span class=\"hljs-params\">name: string | null<\/span>) <\/span>{\n    <span class=\"hljs-keyword\">if<\/span> (name !== <span class=\"hljs-literal\">null<\/span>) {\n        <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">`Hello, <span class=\"hljs-subst\">${name}<\/span>`<\/span>);  <span class=\"hljs-comment\">\/\/ TypeScript \u77e5\u9053\u9019\u88e1\u4e0d\u662f null<\/span>\n    } <span class=\"hljs-keyword\">else<\/span> {\n        <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">\"Hello, stranger\"<\/span>);\n    }\n}\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-22\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u5e38\u898b\u5beb\u6cd5\u901f\u67e5<\/h3>\n\n\n<div class=\"cbc-code-wrapper\"><div class=\"cbc-code-bar\"><button class=\"cbc-copy-button\">Copy<\/button><\/div><pre class=\"wp-block-code\" aria-describedby=\"shcb-language-23\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-comment\">\/\/ \u5beb\u6cd5 1\uff1aif \u5224\u65b7<\/span>\n<span class=\"hljs-keyword\">if<\/span> (value !== <span class=\"hljs-literal\">null<\/span> &amp;&amp; value !== <span class=\"hljs-literal\">undefined<\/span>) {\n    <span class=\"hljs-comment\">\/\/ \u5b89\u5168\u4f7f\u7528 value<\/span>\n}\n\n<span class=\"hljs-comment\">\/\/ \u5beb\u6cd5 2\uff1a\u53ef\u9078\u93c8\uff08Optional Chaining\uff09<\/span>\n<span class=\"hljs-keyword\">const<\/span> name = user?.name;\n<span class=\"hljs-comment\">\/\/ \u2191 \u5982\u679c user \u662f null\/undefined\uff0cname \u5c31\u662f undefined\uff0c\u4e0d\u6703\u5831\u932f<\/span>\n\n<span class=\"hljs-comment\">\/\/ \u5beb\u6cd5 3\uff1a\u7a7a\u503c\u5408\u4f75\uff08Nullish Coalescing\uff09<\/span>\n<span class=\"hljs-keyword\">const<\/span> name = user?.name ?? <span class=\"hljs-string\">\"\u533f\u540d\"<\/span>;\n<span class=\"hljs-comment\">\/\/ \u2191 \u5982\u679c user?.name \u662f null \u6216 undefined\uff0c\u5c31\u7528 \"\u533f\u540d\"<\/span>\n\n<span class=\"hljs-comment\">\/\/ \u5beb\u6cd5 4\uff1a\u975e\u7a7a\u65b7\u8a00\uff08\u8b39\u614e\u4f7f\u7528\uff01\uff09<\/span>\n<span class=\"hljs-keyword\">const<\/span> name = user!.name;\n<span class=\"hljs-comment\">\/\/ \u2191 \u544a\u8a34 TypeScript\u300c\u6211\u4fdd\u8b49 user \u4e0d\u662f null\u300d<\/span>\n<span class=\"hljs-comment\">\/\/ \u5982\u679c\u4f60\u731c\u932f\u4e86\uff0c\u57f7\u884c\u6642\u6703\u7206\u6389<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-23\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u7ffb\u8b6f\u5c0d\u7167<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table>\n<thead>\n<tr>\n<th>\u4ee3\u78bc<\/th>\n<th>\u7ffb\u8b6f<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><code>user?.name<\/code><\/td>\n<td>\u5982\u679c user \u5b58\u5728\uff0c\u53d6 name\uff1b\u5426\u5247\u56de\u50b3 undefined<\/td>\n<\/tr>\n<tr>\n<td><code>name ?? \"\u9810\u8a2d\"<\/code><\/td>\n<td>\u5982\u679c name \u662f null \u6216 undefined\uff0c\u7528 &#8220;\u9810\u8a2d&#8221;<\/td>\n<\/tr>\n<tr>\n<td><code>user!.name<\/code><\/td>\n<td>\u6211\u4fdd\u8b49 user \u4e0d\u662f null\uff08\u5371\u96aa\uff0c\u5c11\u7528\uff09<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u5fc5\u770b\u61c2 vs \u77e5\u9053\u5c31\u597d<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u5fc5\u770b\u61c2\uff08AI \u7522\u51fa\u7684\u7a0b\u5f0f\u78bc\u5929\u5929\u90fd\u6709\uff09<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table>\n<thead>\n<tr>\n<th>\u8a9e\u6cd5<\/th>\n<th>\u7bc4\u4f8b<\/th>\n<th>\u610f\u601d<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Union \u578b\u5225<\/td>\n<td><code>string \\| number<\/code><\/td>\n<td>\u53ef\u4ee5\u662f\u6587\u5b57\u6216\u6578\u5b57<\/td>\n<\/tr>\n<tr>\n<td>Literal \u578b\u5225<\/td>\n<td><code>\"success\" \\| \"error\"<\/code><\/td>\n<td>\u53ea\u80fd\u662f\u9019\u5e7e\u500b\u503c<\/td>\n<\/tr>\n<tr>\n<td>typeof \u6536\u7a84<\/td>\n<td><code>if (typeof x === \"string\")<\/code><\/td>\n<td>\u78ba\u8a8d\u662f\u4ec0\u9ebc\u57fa\u672c\u578b\u5225<\/td>\n<\/tr>\n<tr>\n<td>in \u6536\u7a84<\/td>\n<td><code>if (\"name\" in obj)<\/code><\/td>\n<td>\u78ba\u8a8d\u7269\u4ef6\u6709\u6c92\u6709\u67d0\u5c6c\u6027<\/td>\n<\/tr>\n<tr>\n<td>\u53ef\u8fa8\u8b58\u806f\u5408<\/td>\n<td><code>if (result.status === \"ok\")<\/code><\/td>\n<td>\u7528\u5171\u540c\u5c6c\u6027\u5206\u8fa8\u578b\u5225<\/td>\n<\/tr>\n<tr>\n<td>\u53ef\u9078\u93c8<\/td>\n<td><code>user?.name<\/code><\/td>\n<td>\u5b89\u5168\u5b58\u53d6\uff0c\u4e0d\u6015 null<\/td>\n<\/tr>\n<tr>\n<td>\u7a7a\u503c\u5408\u4f75<\/td>\n<td><code>value ?? \"\u9810\u8a2d\"<\/code><\/td>\n<td>null\/undefined \u6642\u7528\u9810\u8a2d\u503c<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">\u77e5\u9053\u5c31\u597d\uff08\u9047\u5230\u518d\u67e5\uff09<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li><strong>\u81ea\u8a02\u578b\u5225\u5b88\u885b\uff08Type Guard\uff09<\/strong>\uff1a<code>function isFish(pet: Fish | Bird): pet is Fish<\/code> &#8212; \u81ea\u5df1\u5beb\u4e00\u500b\u51fd\u5f0f\u4f86\u5224\u65b7\u578b\u5225\u3002<\/li>\n\n\n<li><strong>never \u578b\u5225<\/strong>\uff1a\u5728\u7aae\u8209\u6240\u6709\u53ef\u80fd\u5f8c\u51fa\u73fe\u7684\u578b\u5225\uff0c\u4ee3\u8868\u300c\u4e0d\u61c9\u8a72\u8d70\u5230\u9019\u88e1\u300d\u3002<\/li>\n\n\n<li><strong>as \u578b\u5225\u65b7\u8a00<\/strong>\uff1a<code>const x = value as string<\/code> &#8212; \u5f37\u5236\u544a\u8a34 TypeScript \u9019\u662f\u4ec0\u9ebc\u578b\u5225\uff0c\u9664\u975e\u4f60\u5f88\u78ba\u5b9a\uff0c\u5426\u5247\u4e0d\u8981\u4e82\u7528\u3002<\/li>\n\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Vibe Coder \u6aa2\u67e5\u9ede<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u770b\u5230 AI \u7522\u51fa\u7684\u7a0b\u5f0f\u78bc\u88e1\u6709 Union \u578b\u5225\u6216\u578b\u5225\u6536\u7a84\u6642\uff0c\u78ba\u8a8d\u4ee5\u4e0b\u5e7e\u9ede\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>[ ] Union \u578b\u5225\u7684\u6bcf\u4e00\u7a2e\u60c5\u6cc1\u90fd\u6709\u8655\u7406\u55ce\uff1f\uff08\u6bd4\u5982 <code>string | number<\/code>\uff0c\u6709\u6c92\u6709\u5206\u5225\u8655\u7406 string \u548c number \u7684\u60c5\u6cc1\uff1f\uff09<\/li>\n\n\n<li>[ ] \u6709\u7528\u5230 <code>!<\/code>\uff08\u975e\u7a7a\u65b7\u8a00\uff09\u55ce\uff1f\u5982\u679c\u6709\uff0cAI \u771f\u7684\u4fdd\u8b49\u90a3\u500b\u503c\u4e0d\u6703\u662f null \u55ce\uff1f<\/li>\n\n\n<li>[ ] \u53ef\u8fa8\u8b58\u806f\u5408\u7684\u6bcf\u500b case \u90fd\u6709\u8986\u84cb\u5230\u55ce\uff1f\uff08\u6bd4\u5982 API \u56de\u61c9\u6709 success \u548c error\uff0c\u5169\u7a2e\u90fd\u6709\u8655\u7406\u55ce\uff1f\uff09<\/li>\n\n\n<li>[ ] \u53ef\u9078\u93c8 <code>?.<\/code> \u5f8c\u9762\u7684\u908f\u8f2f\u5c0d\u55ce\uff1f\uff08\u5982\u679c\u503c\u662f undefined\uff0c\u5f8c\u7e8c\u6709\u6c92\u6709\u6b63\u78ba\u8655\u7406\uff1f\uff09<\/li>\n\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u7e3d\u7d50<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table>\n<thead>\n<tr>\n<th>\u6982\u5ff5<\/th>\n<th>\u4e00\u53e5\u8a71\u8aaa\u660e<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Union \u578b\u5225<\/td>\n<td>\u4e00\u500b\u8b8a\u6578\u53ef\u4ee5\u662f\u597d\u5e7e\u7a2e\u578b\u5225\uff0c\u7528 <code>\\|<\/code> \u9694\u958b<\/td>\n<\/tr>\n<tr>\n<td>Literal \u578b\u5225<\/td>\n<td>\u628a\u5141\u8a31\u7684\u503c\u4e00\u500b\u4e00\u500b\u5217\u51fa\u4f86<\/td>\n<\/tr>\n<tr>\n<td>\u578b\u5225\u6536\u7a84<\/td>\n<td>\u7528 if \u6aa2\u67e5\u5f8c\uff0cTypeScript \u81ea\u52d5\u77e5\u9053\u662f\u54ea\u7a2e\u578b\u5225<\/td>\n<\/tr>\n<tr>\n<td>typeof<\/td>\n<td>\u6aa2\u67e5\u57fa\u672c\u578b\u5225\uff08string\u3001number\u3001boolean\uff09<\/td>\n<\/tr>\n<tr>\n<td>in<\/td>\n<td>\u6aa2\u67e5\u7269\u4ef6\u6709\u6c92\u6709\u67d0\u500b\u5c6c\u6027<\/td>\n<\/tr>\n<tr>\n<td>instanceof<\/td>\n<td>\u6aa2\u67e5\u662f\u4e0d\u662f\u67d0\u500b class \u7684\u5be6\u4f8b<\/td>\n<\/tr>\n<tr>\n<td>\u53ef\u8fa8\u8b58\u806f\u5408<\/td>\n<td>\u7528\u5171\u540c\u5c6c\u6027\uff08\u5982 status\u3001type\uff09\u7684\u503c\u4f86\u5206\u8fa8\u578b\u5225<\/td>\n<\/tr>\n<tr>\n<td>?. \u548c ??<\/td>\n<td>\u5b89\u5168\u8655\u7406 null\/undefined<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\u6838\u5fc3\u5fc3\u6cd5<\/strong>\uff1aTypeScript \u7684 Union \u578b\u5225\u662f\u300c\u5148\u653e\u5bec\uff0c\u518d\u6536\u7a84\u300d\u3002\u5ba3\u544a\u6642\u5141\u8a31\u591a\u7a2e\u578b\u5225\uff0c\u4f7f\u7528\u6642\u903c\u4f60\u5148\u78ba\u8a8d\u662f\u54ea\u4e00\u7a2e\u3002\u770b\u5230 AI \u5beb\u7684\u90a3\u4e9b if \u5224\u65b7\uff0c\u591a\u534a\u662f TypeScript \u903c\u5b83\u5beb\u7684 &#8212; \u4e0d\u5beb\u5c31\u6703\u5831\u932f\u3002<\/p>\n\n\n\n<div id=\"quiz-4be7824d\">\n<style>\n#quiz-4be7824d .badge {\n        display: inline-block;\n        padding: 4px 10px;\n        border-radius: 12px;\n        font-size: 0.75em;\n        font-weight: bold;\n        margin-left: 8px;\n      }#quiz-4be7824d .badge.scenario {\n        background: #ebf8ff;\n        color: #2b6cb0;\n      }#quiz-4be7824d .badge.debug {\n        background: #fef3c7;\n        color: #92400e;\n      }#quiz-4be7824d .question-adv {\n        background: white;\n        border-radius: 10px;\n        padding: 24px;\n        margin: 20px 0;\n        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);\n        border-left: 4px solid #ed8936;\n      }#quiz-4be7824d .question-adv h3 {\n        margin-top: 0;\n        color: #2d3748;\n      }#quiz-4be7824d .code-block {\n        background: #1e1e1e;\n        color: #d4d4d4;\n        padding: 14px;\n        border-radius: 6px;\n        font-family: \"Menlo\", \"Monaco\", \"Courier New\", monospace;\n        font-size: 0.9em;\n        overflow-x: auto;\n        margin: 12px 0;\n        white-space: pre-wrap;\n      }#quiz-4be7824d .options-adv {\n        list-style: none;\n        padding: 0;\n      }#quiz-4be7824d .options-adv li {\n        padding: 14px 16px;\n        margin: 10px 0;\n        border: 2px solid #e2e8f0;\n        border-radius: 8px;\n        cursor: pointer;\n        transition: all 0.2s;\n      }#quiz-4be7824d .options-adv li:hover:not(.disabled) {\n        border-color: #ed8936;\n        background: #fffaf0;\n      }#quiz-4be7824d .options-adv li.disabled {\n        cursor: default;\n        opacity: 0.7;\n      }#quiz-4be7824d .options-adv li.show-answer {\n        border-color: #48bb78;\n        background: #f0fff4;\n      }#quiz-4be7824d .options-adv li.wrong {\n        border-color: #fc8181;\n        background: #fff5f5;\n      }#quiz-4be7824d .feedback-adv {\n        margin-top: 16px;\n        padding: 14px;\n        border-radius: 8px;\n        display: none;\n        line-height: 1.6;\n      }#quiz-4be7824d .feedback-adv.correct {\n        background: #f0fff4;\n        color: #276749;\n        display: block;\n      }#quiz-4be7824d .feedback-adv.wrong {\n        background: #fff5f5;\n        color: #c53030;\n        display: block;\n      }#quiz-4be7824d .feedback-adv \n      .score-adv {\n        text-align: center;\n        font-size: 1.4em;\n        padding: 24px;\n        background: white;\n        border-radius: 10px;\n        margin-top: 24px;\n        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);\n      }#quiz-4be7824d .intro {\n        background: #ebf8ff;\n        padding: 16px;\n        border-radius: 8px;\n        margin-bottom: 20px;\n        color: #2c5282;\n      }\n<\/style>\n<h1>\u9032\u968e\u6e2c\u9a57\uff1aUnion\u3001Literal \u8207\u578b\u5225\u6536\u7a84<\/h1>\n    <div class=\"intro\">\n      <strong>\u6e2c\u9a57\u76ee\u6a19\uff1a<\/strong>\u9a57\u8b49\u4f60\u662f\u5426\u80fd\u5728\u5be6\u969b\u60c5\u5883\u4e2d\u61c9\u7528\u6240\u5b78\u3002<br \/>\n      \u5171 5 \u984c\uff0c\u5305\u542b\u60c5\u5883\u984c\u8207\u932f\u8aa4\u8a3a\u65b7\u984c\u3002\n    <\/div>\n\n    <!-- \u60c5\u5883\u984c 1 -->\n    <div class=\"question-adv\" id=\"qAdv1\">\n      <h3>1. \u4f60\u6b63\u5728\u958b\u767c\u4e00\u500b API \u56de\u61c9\u8655\u7406\u51fd\u5f0f\u3002AI \u5e6b\u4f60\u7522\u51fa\u4e86\u4ee5\u4e0b\u578b\u5225\u5b9a\u7fa9\uff0c\u4f60\u9700\u8981\u5beb\u4e00\u500b\u51fd\u5f0f\u4f86\u8655\u7406\u56de\u61c9\u3002\u54ea\u7a2e\u5beb\u6cd5\u6700\u6b63\u78ba\u4e14\u5b89\u5168\uff1f <span class=\"badge scenario\">\u60c5\u5883\u984c<\/span><\/h3>\n      <div class=\"code-block\">type ApiResponse =\n    | { ok: true; data: User[] }\n    | { ok: false; error: string };\n\nfunction handleResponse(res: ApiResponse) {\n    \/\/ \u8a72\u600e\u9ebc\u5beb\uff1f\n}<\/div>\n      <ul class=\"options-adv\">\n        <li onclick=\"checkAnswerAdv(1, 'A', 'C')\">A. \u76f4\u63a5\u5b58\u53d6 <code>res.data<\/code>\uff0c\u56e0\u70ba\u5927\u90e8\u5206\u6642\u5019 API \u6703\u6210\u529f<\/li>\n        <li onclick=\"checkAnswerAdv(1, 'B', 'C')\">B. \u7528 <code>typeof res.ok === \"boolean\"<\/code> \u4f86\u6536\u7a84\u578b\u5225<\/li>\n        <li onclick=\"checkAnswerAdv(1, 'C', 'C')\">C. \u7528 <code>if (res.ok)<\/code> \u4f86\u5224\u65b7\uff0c\u5728 true \u5206\u652f\u5b58\u53d6 data\uff0c\u5728 false \u5206\u652f\u5b58\u53d6 error<\/li>\n        <li onclick=\"checkAnswerAdv(1, 'D', 'C')\">D. \u7528 <code>res as { ok: true; data: User[] }<\/code> \u5f37\u5236\u65b7\u8a00\u578b\u5225\u5f8c\u5b58\u53d6 data<\/li>\n      <\/ul>\n      <div class=\"feedback-adv\" id=\"fbAdv1\"><\/div>\n    <\/div>\n\n    <!-- \u60c5\u5883\u984c 2 -->\n    <div class=\"question-adv\" id=\"qAdv2\">\n      <h3>2. \u4f60\u8acb AI \u5e6b\u4f60\u5beb\u4e00\u500b\u51fd\u5f0f\uff0c\u63a5\u53d7\u5b57\u4e32\u6216\u6578\u5b57 ID\uff0c\u9700\u8981\u56de\u50b3\u683c\u5f0f\u5316\u5f8c\u7684\u5b57\u4e32\u3002AI \u7522\u51fa\u4e86\u4ee5\u4e0b\u7a0b\u5f0f\u78bc\uff0c\u4f60\u9700\u8981\u5224\u65b7\u54ea\u500b\u7248\u672c\u6700\u7b26\u5408 TypeScript \u7684\u6700\u4f73\u5be6\u8e10\u3002 <span class=\"badge scenario\">\u60c5\u5883\u984c<\/span><\/h3>\n      <div class=\"code-block\">\/\/ \u7248\u672c A\nfunction formatId(id: string | number): string {\n    return &#8220;ID-&#8221; + id.toString();\n}\n\n\/\/ \u7248\u672c B\nfunction formatId(id: string | number): string {\n    if (typeof id === &#8220;number&#8221;) {\n        return &#8220;ID-&#8221; + id.toFixed(0);\n    }\n    return &#8220;ID-&#8221; + id.toUpperCase();\n}\n\n\/\/ \u7248\u672c C\nfunction formatId(id: string | number): string {\n    return &#8220;ID-&#8221; + (id as string).toUpperCase();\n}\n\n\/\/ \u7248\u672c D\nfunction formatId(id: string | number): string {\n    return &#8220;ID-&#8221; + id!.toString();\n}<\/div>\n      <ul class=\"options-adv\">\n        <li onclick=\"checkAnswerAdv(2, 'A', 'B')\">A. \u7248\u672c A &#8212; \u7c21\u55ae\u76f4\u63a5\uff0ctoString() \u5169\u7a2e\u578b\u5225\u90fd\u6709<\/li>\n        <li onclick=\"checkAnswerAdv(2, 'B', 'B')\">B. \u7248\u672c B &#8212; \u7528 typeof \u6536\u7a84\u5f8c\uff0c\u5c0d\u4e0d\u540c\u578b\u5225\u505a\u4e0d\u540c\u8655\u7406<\/li>\n        <li onclick=\"checkAnswerAdv(2, 'C', 'B')\">C. \u7248\u672c C &#8212; \u7528 as \u65b7\u8a00\u6bd4\u8f03\u7c21\u6f54<\/li>\n        <li onclick=\"checkAnswerAdv(2, 'D', 'B')\">D. \u7248\u672c D &#8212; \u7528 ! \u78ba\u4fdd\u4e0d\u662f null \u5c31\u5b89\u5168\u4e86<\/li>\n      <\/ul>\n      <div class=\"feedback-adv\" id=\"fbAdv2\"><\/div>\n    <\/div>\n\n    <!-- \u60c5\u5883\u984c 3 -->\n    <div class=\"question-adv\" id=\"qAdv3\">\n      <h3>3. \u4f60\u5728 code review AI \u7522\u51fa\u7684\u7a0b\u5f0f\u78bc\uff0c\u770b\u5230\u4ee5\u4e0b\u8655\u7406\u4f7f\u7528\u8005\u8cc7\u6599\u7684\u7247\u6bb5\u3002\u6839\u64da\u6587\u7ae0\u7684 Vibe Coder \u6aa2\u67e5\u9ede\uff0c\u54ea\u500b\u554f\u984c\u6700\u61c9\u8a72\u512a\u5148\u78ba\u8a8d\uff1f <span class=\"badge scenario\">\u60c5\u5883\u984c<\/span><\/h3>\n      <div class=\"code-block\">type UserResult =\n    | { status: &#8220;active&#8221;; profile: Profile }\n    | { status: &#8220;banned&#8221;; reason: string }\n    | { status: &#8220;pending&#8221;; verifyUrl: string };\n\nfunction showUser(result: UserResult) {\n    if (result.status === &#8220;active&#8221;) {\n        renderProfile(result.profile);\n    } else if (result.status === &#8220;banned&#8221;) {\n        showBanMessage(result.reason);\n    }\n}<\/div>\n      <ul class=\"options-adv\">\n        <li onclick=\"checkAnswerAdv(3, 'A', 'A')\">A. \u53ef\u8fa8\u8b58\u806f\u5408\u7684 &#8220;pending&#8221; case \u6c92\u6709\u88ab\u8655\u7406\uff0c\u5c11\u4e86\u4e00\u500b\u5206\u652f<\/li>\n        <li onclick=\"checkAnswerAdv(3, 'B', 'A')\">B. \u61c9\u8a72\u7528 typeof \u800c\u4e0d\u662f\u6bd4\u8f03 status \u4f86\u6536\u7a84\u578b\u5225<\/li>\n        <li onclick=\"checkAnswerAdv(3, 'C', 'A')\">C. result \u53ef\u80fd\u662f null\uff0c\u9700\u8981\u5148\u505a null \u6aa2\u67e5<\/li>\n        <li onclick=\"checkAnswerAdv(3, 'D', 'A')\">D. \u61c9\u8a72\u7528 in \u904b\u7b97\u5b50\u4f86\u6aa2\u67e5 profile \u5c6c\u6027\u662f\u5426\u5b58\u5728<\/li>\n      <\/ul>\n      <div class=\"feedback-adv\" id=\"fbAdv3\"><\/div>\n    <\/div>\n\n    <!-- \u932f\u8aa4\u8a3a\u65b7\u984c 1 -->\n    <div class=\"question-adv\" id=\"qAdv4\">\n      <h3>4. \u4ee5\u4e0b\u7a0b\u5f0f\u78bc\u5728 TypeScript \u4e2d\u51fa\u73fe\u7de8\u8b6f\u932f\u8aa4\u3002\u932f\u8aa4\u7684\u6839\u672c\u539f\u56e0\u662f\u4ec0\u9ebc\uff1f <span class=\"badge debug\">\u932f\u8aa4\u8a3a\u65b7<\/span><\/h3>\n      <div class=\"code-block\">function processValue(val: string | number | boolean) {\n    if (typeof val === &#8220;string&#8221;) {\n        console.log(val.toUpperCase());\n    } else {\n        console.log(val.toFixed(2));  \/\/ Error!\n    }\n}<\/div>\n      <ul class=\"options-adv\">\n        <li onclick=\"checkAnswerAdv(4, 'A', 'B')\">A. <code>typeof<\/code> \u7121\u6cd5\u7528\u4f86\u6536\u7a84 Union \u578b\u5225<\/li>\n        <li onclick=\"checkAnswerAdv(4, 'B', 'B')\">B. else \u5340\u584a\u4e2d val \u662f <code>number | boolean<\/code>\uff0cboolean \u6c92\u6709 <code>toFixed<\/code> \u65b9\u6cd5<\/li>\n        <li onclick=\"checkAnswerAdv(4, 'C', 'B')\">C. <code>toFixed<\/code> \u4e0d\u662f number \u7684\u6709\u6548\u65b9\u6cd5<\/li>\n        <li onclick=\"checkAnswerAdv(4, 'D', 'B')\">D. \u61c9\u8a72\u7528 <code>instanceof<\/code> \u800c\u4e0d\u662f <code>typeof<\/code> \u4f86\u6aa2\u67e5 string<\/li>\n      <\/ul>\n      <div class=\"feedback-adv\" id=\"fbAdv4\"><\/div>\n    <\/div>\n\n    <!-- \u932f\u8aa4\u8a3a\u65b7\u984c 2 -->\n    <div class=\"question-adv\" id=\"qAdv5\">\n      <h3>5. \u4ee5\u4e0b\u7a0b\u5f0f\u78bc\u4e2d\uff0c\u958b\u767c\u8005\u8a66\u5716\u5b89\u5168\u5730\u5b58\u53d6\u53ef\u80fd\u70ba null \u7684\u4f7f\u7528\u8005\u8cc7\u6599\uff0c\u4f46\u6709\u4e00\u884c\u5beb\u6cd5\u6709\u6f5b\u5728\u98a8\u96aa\u3002\u662f\u54ea\u4e00\u884c\uff1f <span class=\"badge debug\">\u932f\u8aa4\u8a3a\u65b7<\/span><\/h3>\n      <div class=\"code-block\">function displayUser(user: User | null) {\n    const name = user?.name ?? &#8220;\u533f\u540d&#8221;;        \/\/ \u7b2c 1 \u884c\n    const email = user!.email;                 \/\/ \u7b2c 2 \u884c\n    const age = user?.age ?? 0;                \/\/ \u7b2c 3 \u884c\n    console.log(name, email, age);\n}<\/div>\n      <ul class=\"options-adv\">\n        <li onclick=\"checkAnswerAdv(5, 'A', 'B')\">A. \u7b2c 1 \u884c\uff1a<code>??<\/code> \u904b\u7b97\u5b50\u4e0d\u80fd\u548c <code>?.<\/code> \u4e00\u8d77\u4f7f\u7528<\/li>\n        <li onclick=\"checkAnswerAdv(5, 'B', 'B')\">B. \u7b2c 2 \u884c\uff1a<code>user!<\/code> \u662f\u975e\u7a7a\u65b7\u8a00\uff0c\u5982\u679c user \u662f null \u57f7\u884c\u6642\u6703\u5831\u932f<\/li>\n        <li onclick=\"checkAnswerAdv(5, 'C', 'B')\">C. \u7b2c 3 \u884c\uff1a<code>age<\/code> \u662f\u6578\u5b57\u4e0d\u80fd\u7528 <code>??<\/code> \u7d66\u9810\u8a2d\u503c<\/li>\n        <li onclick=\"checkAnswerAdv(5, 'D', 'B')\">D. \u6240\u6709\u884c\u90fd\u6c92\u554f\u984c\uff0cTypeScript \u6703\u81ea\u52d5\u8655\u7406 null<\/li>\n      <\/ul>\n      <div class=\"feedback-adv\" id=\"fbAdv5\"><\/div>\n    <\/div>\n\n    <div class=\"score-adv\" id=\"scoreAdv\" style=\"display:none;\"><\/div>\n<script>\n\n      let answeredAdv = 0;\n      let correctAdv = 0;\n      const totalAdv = 5;\n      const explanationsAdv = {\n        1: \" \u9019\u662f\u53ef\u8fa8\u8b58\u806f\u5408\uff08Discriminated Union\uff09\u7684\u5178\u578b\u7528\u6cd5\u3002<code>ok<\/code> \u662f\u5171\u540c\u5c6c\u6027\uff0c\u503c\u70ba <code>true<\/code> \u6216 <code>false<\/code>\u3002\u7528 <code>if (res.ok)<\/code> \u5224\u65b7\u5f8c\uff0cTypeScript \u81ea\u52d5\u77e5\u9053 true \u5206\u652f\u88e1\u6709 <code>data<\/code>\uff0cfalse \u5206\u652f\u88e1\u6709 <code>error<\/code>\u3002\u9078\u9805 A \u76f4\u63a5\u5b58\u53d6 data \u6c92\u6709\u6536\u7a84\uff0c\u6703\u5831\u932f\uff1b\u9078\u9805 B \u7684 typeof \u6aa2\u67e5\u6c92\u6709\u610f\u7fa9\uff0c\u56e0\u70ba\u5169\u7a2e\u60c5\u6cc1 ok \u90fd\u662f boolean\uff1b\u9078\u9805 D \u7528 <code>as<\/code> \u5f37\u5236\u65b7\u8a00\u7e5e\u904e\u578b\u5225\u6aa2\u67e5\uff0c\u5982\u679c API \u56de\u50b3\u932f\u8aa4\u7d50\u679c\uff0c\u57f7\u884c\u6642\u6703\u51fa\u554f\u984c\u3002\",\n        2: \" \u7248\u672c B \u4f7f\u7528 <code>typeof<\/code> \u6536\u7a84\uff0c\u91dd\u5c0d\u4e0d\u540c\u578b\u5225\u505a\u4e0d\u540c\u8655\u7406\uff0c\u662f\u6700\u7b26\u5408 TypeScript \u6700\u4f73\u5be6\u8e10\u7684\u505a\u6cd5\u3002\u7248\u672c A \u96d6\u7136\u80fd\u901a\u904e\u7de8\u8b6f\uff08\u56e0\u70ba string \u548c number \u90fd\u6709 toString\uff09\uff0c\u4f46\u6c92\u6709\u5229\u7528\u578b\u5225\u6536\u7a84\u7684\u512a\u52e2\u4f86\u505a\u5dee\u7570\u5316\u8655\u7406\u3002\u7248\u672c C \u4f7f\u7528 <code>as string<\/code> \u65b7\u8a00\u975e\u5e38\u5371\u96aa\uff0c\u5982\u679c id \u662f number\uff0c\u57f7\u884c\u6642 toUpperCase \u6703\u5831\u932f\u3002\u7248\u672c D \u7684 <code>!<\/code> \u975e\u7a7a\u65b7\u8a00\u5728\u9019\u88e1\u6c92\u6709\u610f\u7fa9\uff0c\u56e0\u70ba id \u7684\u578b\u5225\u662f <code>string | number<\/code>\uff0c\u4e0d\u5305\u542b null\/undefined\u3002\",\n        3: \" \u6839\u64da\u6587\u7ae0\u7684 Vibe Coder \u6aa2\u67e5\u9ede\uff0c\u5be9\u67e5\u53ef\u8fa8\u8b58\u806f\u5408\u6642\u8981\u78ba\u8a8d\u300c\u6bcf\u500b case \u90fd\u6709\u8986\u84cb\u5230\u300d\u3002\u9019\u88e1 UserResult \u6709\u4e09\u7a2e status\uff08active\u3001banned\u3001pending\uff09\uff0c\u4f46 showUser \u51fd\u5f0f\u53ea\u8655\u7406\u4e86 active \u548c banned\uff0c\u907a\u6f0f\u4e86 pending \u7684\u60c5\u6cc1\u3002\u9078\u9805 B \u4e0d\u5c0d\uff0c\u56e0\u70ba\u7528\u5171\u540c\u5c6c\u6027\u503c\u4f86\u5206\u8fa8\u6b63\u662f\u53ef\u8fa8\u8b58\u806f\u5408\u7684\u6b63\u78ba\u505a\u6cd5\uff1b\u9078\u9805 C \u4e0d\u5c0d\uff0c\u56e0\u70ba\u53c3\u6578\u578b\u5225\u6c92\u6709\u5305\u542b null\uff1b\u9078\u9805 D \u4e0d\u5c0d\uff0c\u56e0\u70ba\u53ef\u8fa8\u8b58\u806f\u5408\u7528 status \u6bd4\u8f03\u5df2\u7d93\u8db3\u5920\u3002\",\n        4: \" \u554f\u984c\u51fa\u5728\u6536\u7a84\u4e0d\u5920\u5fb9\u5e95\u3002\u7b2c\u4e00\u500b <code>if<\/code> \u6392\u9664\u4e86 string\uff0c\u4f46 else \u5340\u584a\u88e1 val \u7684\u578b\u5225\u662f <code>number | boolean<\/code>\uff0c\u4e0d\u53ea\u662f number\u3002boolean \u6c92\u6709 <code>toFixed<\/code> \u65b9\u6cd5\uff0c\u6240\u4ee5 TypeScript \u5831\u932f\u3002\u4fee\u6b63\u65b9\u5f0f\u662f\u518d\u52a0\u4e00\u5c64 <code>if (typeof val === \\\"number\\\")<\/code> \u4f86\u9032\u4e00\u6b65\u6536\u7a84\uff0c\u5c31\u50cf\u6587\u7ae0\u4e2d\u4e09\u7a2e\u578b\u5225\u7684\u7bc4\u4f8b\u90a3\u6a23\uff0c\u6bcf\u7a2e\u578b\u5225\u90fd\u8981\u5404\u81ea\u8655\u7406\u3002\",\n        5: \" \u7b2c 2 \u884c\u4f7f\u7528\u4e86 <code>user!<\/code>\uff08\u975e\u7a7a\u65b7\u8a00\uff09\uff0c\u9019\u662f\u544a\u8a34 TypeScript\u300c\u6211\u4fdd\u8b49 user \u4e0d\u662f null\u300d\u3002\u4f46\u51fd\u5f0f\u53c3\u6578\u660e\u78ba\u6a19\u793a <code>user: User | null<\/code>\uff0cuser \u5b8c\u5168\u53ef\u80fd\u662f null\u3002\u5982\u679c\u771f\u7684\u662f null\uff0c\u57f7\u884c\u6642\u5b58\u53d6 <code>.email<\/code> \u5c31\u6703\u5831\u932f\u3002\u6587\u7ae0\u63d0\u5230\u975e\u7a7a\u65b7\u8a00\u8981\u300c\u8b39\u614e\u4f7f\u7528\u300d\uff0c\u5982\u679c\u4f60\u731c\u932f\u4e86\uff0c\u57f7\u884c\u6642\u6703\u7206\u6389\u3002\u6b63\u78ba\u505a\u6cd5\u61c9\u8a72\u548c\u7b2c 1\u30013 \u884c\u4e00\u6a23\u4f7f\u7528 <code>?.<\/code> \u548c <code>??<\/code> \u4f86\u5b89\u5168\u8655\u7406\u3002\"\n      };\n\n      function checkAnswerAdv(qNum, selected, correctAns) {\n        const question = document.getElementById(\"qAdv\" + qNum);\n        if (question.classList.contains(\"answered\")) return;\n\n        question.classList.add(\"answered\");\n        answeredAdv++;\n\n        const options = question.querySelectorAll(\".options-adv li\");\n        options.forEach((opt) => {\n          opt.classList.add(\"disabled\");\n          if (opt.textContent.startsWith(correctAns + \".\")) {\n            opt.classList.add(\"show-answer\");\n          }\n        });\n\n        const feedback = document.getElementById(\"fbAdv\" + qNum);\n        if (selected === correctAns) {\n          correctAdv++;\n          feedback.className = \"feedback-adv correct\";\n          feedback.innerHTML = \"\u2713 \u6b63\u78ba\uff01\" + explanationsAdv[qNum];\n        } else {\n          feedback.className = \"feedback-adv wrong\";\n          feedback.innerHTML =\n            \"\u2717 \u932f\u8aa4\u3002\u6b63\u78ba\u7b54\u6848\u662f \" + correctAns + \"\u3002\" + explanationsAdv[qNum];\n          options.forEach((opt) => {\n            if (opt.textContent.startsWith(selected + \".\")) {\n              opt.classList.add(\"wrong\");\n            }\n          });\n        }\n\n        if (answeredAdv === totalAdv) {\n          const scoreDiv = document.getElementById(\"scoreAdv\");\n          scoreDiv.style.display = \"block\";\n          let msg = \"\";\n          if (correctAdv === totalAdv) msg = \"\ud83c\udfaf \u5b8c\u7f8e\uff01\u4f60\u5df2\u7d93\u6e96\u5099\u597d\u5be6\u6230\u4e86\uff01\";\n          else if (correctAdv >= Math.ceil(totalAdv * 0.8))\n            msg = \"\ud83d\udcaa \u5f88\u68d2\uff01\u518d\u8907\u7fd2\u4e00\u4e0b\u932f\u7684\u984c\u76ee\";\n          else if (correctAdv >= Math.ceil(totalAdv * 0.6))\n            msg = \"\ud83d\udcd6 \u5efa\u8b70\u91cd\u8b80\u76f8\u95dc\u6bb5\u843d\u5f8c\u518d\u8a66\u4e00\u6b21\";\n          else msg = \"\ud83d\udd04 \u5efa\u8b70\u91cd\u65b0\u95b1\u8b80\u6587\u4ef6\uff0c\u7279\u5225\u6ce8\u610f\u64cd\u4f5c\u6d41\u7a0b\";\n          scoreDiv.innerHTML =\n            \"\u6e2c\u9a57\u5b8c\u6210\uff01\u5f97\u5206\uff1a\" + correctAdv + \" \/ \" + totalAdv + \"<br>\" + msg;\n        }\n      }\n    \n<\/script>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\u6e2c\u9a57\uff1aUnion\u3001Literal \u8207\u578b\u5225\u6536\u7a84 \u5171 5 \u984c\uff0c\u9ede\u9078\u7b54\u6848\u5f8c\u6703\u7acb\u5373\u986f\u793a\u7d50\u679c 1. \u5728 TypeScri [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"rolpb_likes":0,"footnotes":""},"categories":[629],"tags":[26],"class_list":["post-701","post","type-post","status-publish","format-standard","hentry","category-typescript","tag-typescript"],"blocksy_meta":{"styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":7}},"_links":{"self":[{"href":"https:\/\/blog.itsmygo.uk\/wordpress\/wp-json\/wp\/v2\/posts\/701","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.itsmygo.uk\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.itsmygo.uk\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.itsmygo.uk\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.itsmygo.uk\/wordpress\/wp-json\/wp\/v2\/comments?post=701"}],"version-history":[{"count":1,"href":"https:\/\/blog.itsmygo.uk\/wordpress\/wp-json\/wp\/v2\/posts\/701\/revisions"}],"predecessor-version":[{"id":706,"href":"https:\/\/blog.itsmygo.uk\/wordpress\/wp-json\/wp\/v2\/posts\/701\/revisions\/706"}],"wp:attachment":[{"href":"https:\/\/blog.itsmygo.uk\/wordpress\/wp-json\/wp\/v2\/media?parent=701"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.itsmygo.uk\/wordpress\/wp-json\/wp\/v2\/categories?post=701"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.itsmygo.uk\/wordpress\/wp-json\/wp\/v2\/tags?post=701"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}