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itemtype="https://schema.org/ListItem" class="breadcrumbs__item"><span class="breadcrumbs__link" itemprop="item name">模拟题四</span><meta itemprop="position" content="1"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active"><span class="breadcrumbs__link" itemprop="item name">基础：什么是 TypeScript 泛型</span><meta itemprop="position" content="2"></li></ul></nav><div class="tocCollapsible_jdIR theme-doc-toc-mobile tocMobile_TmEX"><button type="button" class="clean-btn tocCollapsibleButton_Fzxq">On this page</button></div><div class="theme-doc-markdown markdown"><h1>什么是 TypeScript 泛型</h1><h2 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="相关问题">相关问题<a class="hash-link" href="#相关问题" title="Direct link to heading"></a></h2><ul><li>TypeScript 泛型的作用是什么</li></ul><h2 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="回答关键点">回答关键点<a class="hash-link" href="#回答关键点" title="Direct link to heading"></a></h2><p><code>工具</code> <code>使用时指定类型</code></p><p>TypeScript 泛型是一种工具。它能让开发者不在定义时指定类型，而在使用时指定类型。</p><h2 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="知识点深入">知识点深入<a class="hash-link" href="#知识点深入" title="Direct link to heading"></a></h2><h3 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="1-泛型类">1. 泛型类<a class="hash-link" href="#1-泛型类" title="Direct link to heading"></a></h3><p>类型参数在类名后面的尖括号中指定。泛型类可以具有泛型字段或方法。</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">class</span><span class="token plain"> </span><span class="token class-name maybe-class-name">HZFEMember</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name punctuation" style="color:#393A34">,</span><span class="token class-name"> </span><span class="token class-name constant" style="color:#36acaa">U</span><span class="token class-name operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword" style="color:#00009f">private</span><span class="token plain"> id</span><span class="token operator" style="color:#393A34">!</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword" style="color:#00009f">private</span><span class="token plain"> name</span><span class="token operator" style="color:#393A34">!</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">U</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token function" style="color:#d73a49">setMember</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">U</span><span class="token punctuation" style="color:#393A34">)</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">void</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword" style="color:#00009f">this</span><span class="token punctuation" style="color:#393A34">.</span><span class="token property-access">id</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> id</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword" style="color:#00009f">this</span><span class="token punctuation" style="color:#393A34">.</span><span class="token property-access">name</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> name</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token function" style="color:#d73a49">show</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">void</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token template-string string" style="color:#e3116c">ID: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation keyword" style="color:#00009f">this</span><span class="token template-string interpolation punctuation" style="color:#393A34">.</span><span class="token template-string interpolation property-access">id</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string string" style="color:#e3116c">, Name: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation keyword" style="color:#00009f">this</span><span class="token template-string interpolation punctuation" style="color:#393A34">.</span><span class="token template-string interpolation property-access">name</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> member1 </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">new</span><span class="token plain"> </span><span class="token class-name maybe-class-name">HZFEMember</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name builtin">number</span><span class="token class-name punctuation" style="color:#393A34">,</span><span class="token class-name"> </span><span class="token class-name builtin">string</span><span class="token class-name operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">member1</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">setMember</span><span class="token punctuation" style="color:#393A34">(</span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"QingZhen"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">member1</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">show</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// ID: 1, Name: QingZhen</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> member2 </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">new</span><span class="token plain"> </span><span class="token class-name maybe-class-name">HZFEMember</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name builtin">string</span><span class="token class-name punctuation" style="color:#393A34">,</span><span class="token class-name"> </span><span class="token class-name builtin">string</span><span class="token class-name operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">member2</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">setMember</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"02"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"Aki"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">member2</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">show</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// ID: 02, Name: Aki</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><h3 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="2-泛型接口">2. 泛型接口<a class="hash-link" href="#2-泛型接口" title="Direct link to heading"></a></h3><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">interface</span><span class="token plain"> </span><span class="token class-name maybe-class-name">HZFEMember</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name punctuation" style="color:#393A34">,</span><span class="token class-name"> </span><span class="token class-name constant" style="color:#36acaa">U</span><span class="token class-name operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">U</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> member1</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">HZFEMember</span><span class="token operator" style="color:#393A34"><</span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token builtin">string</span><span class="token operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"QingZhen"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token template-string string" style="color:#e3116c">ID: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation">member1</span><span class="token template-string interpolation punctuation" style="color:#393A34">.</span><span class="token template-string interpolation property-access">id</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string string" style="color:#e3116c">, Name: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation">member1</span><span class="token template-string interpolation punctuation" style="color:#393A34">.</span><span class="token template-string interpolation property-access">name</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// ID: 1, Name: QingZhen</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> member2</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">HZFEMember</span><span class="token operator" style="color:#393A34"><</span><span class="token builtin">string</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token builtin">string</span><span class="token operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"02"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"Aki"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token template-string string" style="color:#e3116c">ID: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation">member2</span><span class="token template-string interpolation punctuation" style="color:#393A34">.</span><span class="token template-string interpolation property-access">id</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string string" style="color:#e3116c">, Name: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation">member2</span><span class="token template-string interpolation punctuation" style="color:#393A34">.</span><span class="token template-string interpolation property-access">name</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// ID: 02, Name: Aki</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><p><strong>函数类型的泛型接口</strong></p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">interface</span><span class="token plain"> </span><span class="token class-name maybe-class-name">ShowHZFEMember</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name punctuation" style="color:#393A34">,</span><span class="token class-name"> </span><span class="token class-name constant" style="color:#36acaa">U</span><span class="token class-name operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">U</span><span class="token punctuation" style="color:#393A34">)</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">void</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> showHZFEMember</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">ShowHZFEMember</span><span class="token operator" style="color:#393A34"><</span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token builtin">string</span><span class="token operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">function</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">id</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> name</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token template-string string" style="color:#e3116c">ID: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation">id</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string string" style="color:#e3116c">, Name: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation">name</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token function" style="color:#d73a49">showHZFEMember</span><span class="token punctuation" style="color:#393A34">(</span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"QingZhen"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// ID: 1, Name: QingZhen</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> showHZFEMember2</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">ShowHZFEMember</span><span class="token operator" style="color:#393A34"><</span><span class="token builtin">string</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token builtin">string</span><span class="token operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">function</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">id</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> name</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token template-string string" style="color:#e3116c">ID: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation">id</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string string" style="color:#e3116c">, Name: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation">name</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token function" style="color:#d73a49">showHZFEMember2</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"02"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"Aki"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// ID: 02, Name: Aki</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><h3 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="3-泛型约束">3. 泛型约束<a class="hash-link" href="#3-泛型约束" title="Direct link to heading"></a></h3><p>在下面的例子中访问 member 的 id 属性时，因为编译器并不能证明 member 中有 id 属性，所以会报错。</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">function</span><span class="token plain"> </span><span class="token generic-function function" style="color:#d73a49">getHZFEMember</span><span class="token generic-function generic class-name operator" style="color:#393A34"><</span><span class="token generic-function generic class-name constant" style="color:#36acaa">T</span><span class="token generic-function generic class-name operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">member</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">)</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token template-string string" style="color:#e3116c">ID: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation">member</span><span class="token template-string interpolation punctuation" style="color:#393A34">.</span><span class="token template-string interpolation property-access">id</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// Property 'id' does not exist on type 'T'.</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">return</span><span class="token plain"> member</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><p>如果我们想要限制函数只能处理带有 id 属性的类型，就需要列出对于 T 的约束要求。我们可以定义一个接口来描述约束条件，创建一个包含 id 属性的接口，使用这个接口和 <code>extends</code> 关键字来实现约束。</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">interface</span><span class="token plain"> </span><span class="token class-name maybe-class-name">Member</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">function</span><span class="token plain"> </span><span class="token generic-function function" style="color:#d73a49">getHZFEMember</span><span class="token generic-function generic class-name operator" style="color:#393A34"><</span><span class="token generic-function generic class-name constant" style="color:#36acaa">T</span><span class="token generic-function generic class-name"> </span><span class="token generic-function generic class-name keyword" style="color:#00009f">extends</span><span class="token generic-function generic class-name"> </span><span class="token generic-function generic class-name maybe-class-name">Member</span><span class="token generic-function generic class-name operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">member</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">)</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token template-string string" style="color:#e3116c">ID: </span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">${</span><span class="token template-string interpolation">member</span><span class="token template-string interpolation punctuation" style="color:#393A34">.</span><span class="token template-string interpolation property-access">id</span><span class="token template-string interpolation interpolation-punctuation punctuation" style="color:#393A34">}</span><span class="token template-string template-punctuation string" style="color:#e3116c">`</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">return</span><span class="token plain"> member</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token function" style="color:#d73a49">getHZFEMember</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"QingZhen"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// Argument of type 'string' is not assignable to parameter of type 'Member'.</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token function" style="color:#d73a49">getHZFEMember</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"QingZhen"</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// ID: 1</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><h3 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="4-内置的工具类型">4. 内置的工具类型<a class="hash-link" href="#4-内置的工具类型" title="Direct link to heading"></a></h3><p>TypeScript 提供了一些内置的工具类型，本质上也是通过范型来实现的。下面，我们通过几种常用的类型来看看它们是怎么实现的。</p><h4 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="41-partialtype">4.1 Partial<Type<!-- -->><a class="hash-link" href="#41-partialtype" title="Direct link to heading"></a></h4><p>通过将 Type 中的所有属性都设置为可选来构造一个新的类型。</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">interface</span><span class="token plain"> </span><span class="token class-name maybe-class-name">Member</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">string</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> age</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> hzfer</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">Member</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"Qingzhen"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// Property 'age' is missing in type '{ id: number; name: string; }' but required in type 'Member'.</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">HZFEMember</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token maybe-class-name">Partial</span><span class="token operator" style="color:#393A34"><</span><span class="token maybe-class-name">Member</span><span class="token operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> hzfer2</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">HZFEMember</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"Qingzhen"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// No errors</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><p>源码：</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">Partial</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">[</span><span class="token constant" style="color:#36acaa">P</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">in</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">keyof</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">]</span><span class="token operator" style="color:#393A34">?</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">[</span><span class="token constant" style="color:#36acaa">P</span><span class="token punctuation" style="color:#393A34">]</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><h4 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="42-requiredtype">4.2 Required<Type<!-- -->><a class="hash-link" href="#42-requiredtype" title="Direct link to heading"></a></h4><p>通过将 Type 中的所有属性都设置为必选来构造一个新的类型。和 Partial 相反。</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">interface</span><span class="token plain"> </span><span class="token class-name maybe-class-name">Member</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">string</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> age</span><span class="token operator" style="color:#393A34">?</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> hzfer</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">Member</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"Qingzhen"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// No errors</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">HZFEMember</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token maybe-class-name">Required</span><span class="token operator" style="color:#393A34"><</span><span class="token maybe-class-name">Member</span><span class="token operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> hzfer2</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">HZFEMember</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"Qingzhen"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// Property 'age' is missing in type '{ id: number; name: string; }' but required in type 'Required<Member>'</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><p>源码：</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">Required</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">[</span><span class="token constant" style="color:#36acaa">P</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">in</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">keyof</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">]</span><span class="token operator" style="color:#393A34">-</span><span class="token operator" style="color:#393A34">?</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">[</span><span class="token constant" style="color:#36acaa">P</span><span class="token punctuation" style="color:#393A34">]</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><h4 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="43-excludeuniontype-excludedmembers">4.3 Exclude<UnionType, ExcludedMembers><a class="hash-link" href="#43-excludeuniontype-excludedmembers" title="Direct link to heading"></a></h4><p>从联合类型 UnionType 中排除 ExcludedMembers 中的所有联合成员来构造一个新的类型。</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">HZFEMemberProps</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token maybe-class-name">Exclude</span><span class="token operator" style="color:#393A34"><</span><span class="token string" style="color:#e3116c">"id"</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">|</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"name"</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">|</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"age"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"age"</span><span class="token operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> hzferProp</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">HZFEMemberProps</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"age"</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// Type '"age"' is not assignable to type 'HZFEMemberProps'.</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><p>源码：</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">Exclude</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name punctuation" style="color:#393A34">,</span><span class="token class-name"> </span><span class="token class-name constant" style="color:#36acaa">U</span><span class="token class-name operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">extends</span><span class="token plain"> </span><span class="token class-name constant" style="color:#36acaa">U</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">?</span><span class="token plain"> </span><span class="token builtin">never</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><h4 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="44-picktype-keys">4.4 Pick<Type, Keys><a class="hash-link" href="#44-picktype-keys" title="Direct link to heading"></a></h4><p>从一个已有的类型 Type 中选择一组属性 Keys 来构造一个新的类型。</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">interface</span><span class="token plain"> </span><span class="token class-name maybe-class-name">Member</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">string</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> age</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">HZFEMember</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token maybe-class-name">Pick</span><span class="token operator" style="color:#393A34"><</span><span class="token maybe-class-name">Member</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"id"</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">|</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"name"</span><span class="token operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> hzfer</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">HZFEMember</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"QingZhen"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> age</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">18</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// Object literal may only specify known properties, and 'age' does not exist in type 'HZFEMember'.</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><p>源码：</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">Pick</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name punctuation" style="color:#393A34">,</span><span class="token class-name"> </span><span class="token class-name constant" style="color:#36acaa">K</span><span class="token class-name"> </span><span class="token class-name keyword" style="color:#00009f">extends</span><span class="token class-name"> </span><span class="token class-name keyword" style="color:#00009f">keyof</span><span class="token class-name"> </span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">[</span><span class="token constant" style="color:#36acaa">P</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">in</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">K</span><span class="token punctuation" style="color:#393A34">]</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">[</span><span class="token constant" style="color:#36acaa">P</span><span class="token punctuation" style="color:#393A34">]</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><h4 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="45-omittype-keys">4.5 Omit<Type, Keys><a class="hash-link" href="#45-omittype-keys" title="Direct link to heading"></a></h4><p>从一个已有的类型 Type 中移除一组属性 Keys 来构造一个新的类型。</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">interface</span><span class="token plain"> </span><span class="token class-name maybe-class-name">Member</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">string</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> age</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">HZFEMember</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token maybe-class-name">Omit</span><span class="token operator" style="color:#393A34"><</span><span class="token maybe-class-name">Member</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"id"</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">|</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"age"</span><span class="token operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> hzfer</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token maybe-class-name">HZFEMember</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// Object literal may only specify known properties, and 'id' does not exist in type 'HZFEMember'.</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token string" style="color:#e3116c">"QingZhen"</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><p>源码：</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">Omit</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name punctuation" style="color:#393A34">,</span><span class="token class-name"> </span><span class="token class-name constant" style="color:#36acaa">K</span><span class="token class-name"> </span><span class="token class-name keyword" style="color:#00009f">extends</span><span class="token class-name"> </span><span class="token class-name keyword" style="color:#00009f">keyof</span><span class="token class-name"> </span><span class="token class-name builtin">any</span><span class="token class-name operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token maybe-class-name">Pick</span><span class="token operator" style="color:#393A34"><</span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token maybe-class-name">Exclude</span><span class="token operator" style="color:#393A34"><</span><span class="token keyword" style="color:#00009f">keyof</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">K</span><span class="token operator" style="color:#393A34">>></span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><h4 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="46-returntypetype">4.6 ReturnType<Type<!-- -->><a class="hash-link" href="#46-returntypetype" title="Direct link to heading"></a></h4><p>构造一个由函数的返回值的类型 Type 组成的类型。</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">interface</span><span class="token plain"> </span><span class="token class-name maybe-class-name">GetHZFEMember</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">)</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> id</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> name</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">string</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> age</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">HZFEMember</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token maybe-class-name">ReturnType</span><span class="token operator" style="color:#393A34"><</span><span class="token maybe-class-name">GetHZFEMember</span><span class="token operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// type HZFEMember = { id: number; name: string; age: number; };</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><p>源码：</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">ReturnType</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name"> </span><span class="token class-name keyword" style="color:#00009f">extends</span><span class="token class-name"> </span><span class="token class-name punctuation" style="color:#393A34">(</span><span class="token class-name spread operator" style="color:#393A34">...</span><span class="token class-name">args</span><span class="token class-name operator" style="color:#393A34">:</span><span class="token class-name"> </span><span class="token class-name builtin">any</span><span class="token class-name punctuation" style="color:#393A34">)</span><span class="token class-name"> </span><span class="token class-name arrow operator" style="color:#393A34">=></span><span class="token plain"> </span><span class="token builtin">any</span><span class="token operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">extends</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token spread operator" style="color:#393A34">...</span><span class="token plain">args</span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">any</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token arrow operator" style="color:#393A34">=></span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">infer</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">R</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token operator" style="color:#393A34">?</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">R</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">any</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><h4 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="47-infer">4.7 infer<a class="hash-link" href="#47-infer" title="Direct link to heading"></a></h4><p>infer 表示在 extends 条件语句中待推断的类型变量。</p><p>上文的 ReturnType 源码中的 <code>infer R</code> 就代表了待推断的函数的返回值类型。</p><p>借助这个能力，我们可以通过 infer 来实现 tuple 转 union：</p><div class="codeBlockContainer_I0IT language-ts theme-code-block"><div class="codeBlockContent_wNvx" style="color:#393A34;background-color:#f6f8fa"><pre tabindex="0" class="prism-code language-ts codeBlock_jd64 thin-scrollbar"><code class="codeBlockLines_mRuA"><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic">// 如果泛型参数 T 满足约束条件 Array<infer I>，那么就返回这个类型变量</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">TypeOfArrayItem</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name constant" style="color:#36acaa">T</span><span class="token class-name operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">T</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">extends</span><span class="token plain"> </span><span class="token class-name known-class-name class-name">Array</span><span class="token class-name operator" style="color:#393A34"><</span><span class="token class-name keyword" style="color:#00009f">infer</span><span class="token class-name"> </span><span class="token class-name constant" style="color:#36acaa">I</span><span class="token class-name operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token operator" style="color:#393A34">?</span><span class="token plain"> </span><span class="token constant" style="color:#36acaa">I</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">:</span><span class="token plain"> </span><span class="token builtin">never</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">MyTuple</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">[</span><span class="token builtin">string</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token builtin">number</span><span class="token punctuation" style="color:#393A34">]</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">type</span><span class="token plain"> </span><span class="token class-name maybe-class-name">MyUnion</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token maybe-class-name">TypeOfArrayItem</span><span class="token operator" style="color:#393A34"><</span><span class="token maybe-class-name">MyTuple</span><span class="token operator" style="color:#393A34">></span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// string | number</span><br></span></code></pre><button type="button" aria-label="Copy code to clipboard" title="Copy" class="copyButton_eDfN clean-btn"><span class="copyButtonIcons_W9eQ" aria-hidden="true"><svg class="copyButtonIcon_XEyF" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_i9w9" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div><h2 class="anchor anchorWithHideOnScrollNavbar_R0VQ" id="参考资料">参考资料<a class="hash-link" href="#参考资料" title="Direct link to heading"></a></h2><ol><li><a href="https://www.typescriptlang.org/docs/handbook/2/generics.html" target="_blank" rel="noopener noreferrer">Generics</a></li></ol></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages navigation"><div class="pagination-nav__item"><a class="pagination-nav__link" href="/awesome-interview/book4/frame-react-vs-vue"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">框架：谈谈 React 和 Vue 的区别</div></a></div><div class="pagination-nav__item pagination-nav__item--next"><a class="pagination-nav__link" href="/awesome-interview/book4/css-vertical-horizontal-center"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">样式：水平垂直居中方案</div></a></div></nav></div></div><div class="col col--3"><div class="tableOfContents_cNA8 thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="#相关问题" class="table-of-contents__link toc-highlight">相关问题</a></li><li><a href="#回答关键点" class="table-of-contents__link toc-highlight">回答关键点</a></li><li><a href="#知识点深入" class="table-of-contents__link toc-highlight">知识点深入</a><ul><li><a href="#1-泛型类" class="table-of-contents__link toc-highlight">1. 泛型类</a></li><li><a href="#2-泛型接口" class="table-of-contents__link toc-highlight">2. 泛型接口</a></li><li><a href="#3-泛型约束" class="table-of-contents__link toc-highlight">3. 泛型约束</a></li><li><a href="#4-内置的工具类型" class="table-of-contents__link toc-highlight">4. 内置的工具类型</a><ul><li><a href="#41-partialtype" class="table-of-contents__link toc-highlight">4.1 Partial<Type></a></li><li><a href="#42-requiredtype" class="table-of-contents__link toc-highlight">4.2 Required<Type></a></li><li><a href="#43-excludeuniontype-excludedmembers" class="table-of-contents__link toc-highlight">4.3 Exclude<UnionType, ExcludedMembers></a></li><li><a href="#44-picktype-keys" class="table-of-contents__link toc-highlight">4.4 Pick<Type, Keys></a></li><li><a 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