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120 lines
5.5 KiB
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<article id="wikiArticle">
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<div></div>
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<p><code><strong>Reflect</strong></code><strong><code>.construct()</code></strong> 方法的行为有点像 <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/new"><code>new</code> 操作符</a> 构造函数 ， 相当于运行 <code>new target(...args)</code>.</p>
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<h2 id="语法">语法</h2>
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<pre><code class="language-javascript">Reflect.construct(target, argumentsList[, newTarget])
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</code></pre>
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<h3 id="参数">参数</h3>
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<dl>
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<dt><code>target</code></dt>
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<dd>被运行的目标函数</dd>
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<dt><code>argumentsList</code></dt>
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<dd>调用构造函数的数组或者伪数组</dd>
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<dt><code>newTarget</code> <span class="inlineIndicator optional optionalInline">可选</span></dt>
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<dd>该参数为构造函数， 参考 <code><a href="/en-US/docs/Web/JavaScript/Reference/Operators/new.target">new.target</a></code> 操作符，如果没有newTarget参数， 默认和<code>target一样</code></dd>
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</dl>
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<h3 id="Errors_thrown">Errors thrown</h3>
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<p>抛出<a href="Reference/Global_Objects/TypeError" title="TypeError（类型错误） 对象用来表示值的类型非预期类型时发生的错误。"><code>TypeError</code></a>,异常， 如果target或者newTarget不是构造函数</p>
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<h2 id="描述">描述</h2>
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<p><code>Reflect.construct允许你使用可变的参数来调用构造函数</code> </p>
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<pre><code class="language-javascript">var obj = new Foo(...args);
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var obj = Reflect.construct(Foo, args); </code></pre>
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<h2 id="实例">实例</h2>
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<h3 id="使用_Reflect.construct()">使用 <code>Reflect.construct()</code></h3>
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<pre><code class="language-javascript">var d = Reflect.construct(Date, [1776, 6, 4]);
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d instanceof Date; // true
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d.getFullYear(); // 1776
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</code></pre>
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<h3 id="使用_newTarget_参数">使用 <code>newTarget</code> 参数</h3>
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<p>参考 <a href="/en-US/docs/Web/JavaScript/Reference/Classes">classes</a> 获取更多有关子类的信息， 和<code><a href="/en-US/docs/Web/JavaScript/Reference/Operators/new.target">new.target</a></code> 操作符的信息</p>
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<pre><code class="language-javascript">function someConstructor() {}
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var result = Reflect.construct(Array, [], someConstructor);
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Reflect.getPrototypeOf(result); // 输出：someConstructor.prototype
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Array.isArray(result); // true
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</code></pre>
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<h2 id="规范">规范</h2>
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<table class="standard-table">
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<tbody>
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<tr>
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<th scope="col">Specification</th>
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<th scope="col">Status</th>
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<th scope="col">Comment</th>
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</tr>
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<tr>
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<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-reflect.construct" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Reflect.construct</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td>Initial definition.</td>
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</tr>
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<tr>
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<td><a class="external" href="https://tc39.github.io/ecma262/#sec-reflect.construct" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">Reflect.construct</small></a></td>
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<td><span class="spec-Draft">Draft</span></td>
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<td> </td>
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</tr>
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</tbody>
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</table>
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<h2 id="浏览器兼容">浏览器兼容</h2>
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<p></p><div class="blockIndicator warning"><strong><a class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">We're converting our compatibility data into a machine-readable JSON format</a></strong>.
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This compatibility table still uses the old format,
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because we haven't yet converted the data it contains.
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<strong><a class="new" href="/zh-CN/docs/MDN/Contribute/Structures/Compatibility_tables" rel="nofollow">Find out how you can help!</a></strong></div>
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<div class="htab">
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<a id="AutoCompatibilityTable" name="AutoCompatibilityTable"></a>
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<ul>
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<li class="selected"><a>Desktop</a></li>
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<li><a>Mobile</a></li>
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</ul>
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</div><p></p>
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<div id="compat-desktop">
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<table class="compat-table">
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<tbody>
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<tr>
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<th>Feature</th>
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<th>Chrome</th>
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<th>Firefox (Gecko)</th>
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<th>Internet Explorer</th>
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<th>Opera</th>
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<th>Safari</th>
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</tr>
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<tr>
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<td>Basic support</td>
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<td>49</td>
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<td><a href="/en-US/Firefox/Releases/42" title="Released on 2015-11-03.">42</a> (42)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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</tr>
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</tbody>
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</table>
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</div>
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<div id="compat-mobile">
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<table class="compat-table">
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<tbody>
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<tr>
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<th>Feature</th>
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<th>Android</th>
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<th>Chrome for Android</th>
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<th>Firefox Mobile (Gecko)</th>
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<th>IE Mobile</th>
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<th>Opera Mobile</th>
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<th>Safari Mobile</th>
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</tr>
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<tr>
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<td>Basic support</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td>42.0 (42)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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</tr>
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</tbody>
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</table>
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</div>
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<h2 id="相关链接">相关链接</h2>
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<ul>
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<li><a href="Reference/Global_Objects/Reflect" title="Reflect 是一个内置的对象，它提供拦截 JavaScript 操作的方法。这些方法与处理器对象的方法相同。Reflect不是一个函数对象，因此它是不可构造的。"><code>Reflect</code></a></li>
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<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/new"><code>new</code></a></li>
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<li><code><a href="/en-US/docs/Web/JavaScript/Reference/Operators/new.target">new.target</a></code></li>
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</ul>
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</article> |