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+---
+title: Reflect.has()
+slug: Web/JavaScript/Reference/Global_Objects/Reflect/has
+translation_of: Web/JavaScript/Reference/Global_Objects/Reflect/has
+---
+<div>{{JSRef}}</div>
+
+<p>静态方法 <code><strong>Reflect</strong></code><strong><code>.has()</code></strong> 作用与 <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/in"><code>in</code> 操作符</a> 相同。</p>
+
+<h2 id="句法">句法</h2>
+
+<pre class="syntaxbox">Reflect.has(target, propertyKey)
+</pre>
+
+<h3 id="参数">参数</h3>
+
+<dl>
+ <dt><code>target</code></dt>
+ <dd>目标对象.</dd>
+ <dt><code>propertyKey</code></dt>
+ <dd>属性名,需要检查目标对象是否存在此属性。</dd>
+</dl>
+
+<h3 id="返回值">返回值</h3>
+
+<p>一个 {{jsxref("Boolean")}} 类型的对象指示是否存在此属性。</p>
+
+<h3 id="异常">异常</h3>
+
+<p>如果目标对象并非{{jsxref("Object")}} 类型,抛出{{jsxref("TypeError")}}。</p>
+
+<h2 id="描述">描述</h2>
+
+<p><code>Reflect.has</code> 用于检查一个对象是否拥有某个属性, 相当于<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/in"><code>in</code> 操作符</a> 。</p>
+
+<h2 id="示例">示例</h2>
+
+<h3 id="使用_Reflect.has()">使用 <code>Reflect.has()</code></h3>
+
+<pre class="brush: js">Reflect.has({x: 0}, "x"); // true
+Reflect.has({x: 0}, "y"); // false
+
+// 如果该属性存在于原型链中,返回true
+Reflect.has({x: 0}, "toString");
+
+// Proxy 对象的 .has() 句柄方法
+obj = new Proxy({}, {
+ has(t, k) { return k.startsWith("door"); }
+});
+Reflect.has(obj, "doorbell"); // true
+Reflect.has(obj, "dormitory"); // false
+</pre>
+
+<h2 id="规范">规范</h2>
+
+<table class="standard-table">
+ <tbody>
+ <tr>
+ <th scope="col">Specification</th>
+ <th scope="col">Status</th>
+ <th scope="col">Comment</th>
+ </tr>
+ <tr>
+ <td>{{SpecName('ES6', '#sec-reflect.has', 'Reflect.has')}}</td>
+ <td>{{Spec2('ES6')}}</td>
+ <td>Initial definition.</td>
+ </tr>
+ <tr>
+ <td>{{SpecName('ESDraft', '#sec-reflect.has', 'Reflect.has')}}</td>
+ <td>{{Spec2('ESDraft')}}</td>
+ <td> </td>
+ </tr>
+ </tbody>
+</table>
+
+<h2 id="浏览器兼容性">浏览器兼容性</h2>
+
+<p>{{CompatibilityTable}}</p>
+
+<div id="compat-desktop">
+<table class="compat-table">
+ <tbody>
+ <tr>
+ <th>Feature</th>
+ <th>Chrome</th>
+ <th>Firefox (Gecko)</th>
+ <th>Internet Explorer</th>
+ <th>Opera</th>
+ <th>Safari</th>
+ </tr>
+ <tr>
+ <td>Basic support</td>
+ <td>49</td>
+ <td>{{CompatGeckoDesktop(42)}}</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatNo}}</td>
+ </tr>
+ </tbody>
+</table>
+</div>
+
+<div id="compat-mobile">
+<table class="compat-table">
+ <tbody>
+ <tr>
+ <th>Feature</th>
+ <th>Android</th>
+ <th>Chrome for Android</th>
+ <th>Firefox Mobile (Gecko)</th>
+ <th>IE Mobile</th>
+ <th>Opera Mobile</th>
+ <th>Safari Mobile</th>
+ </tr>
+ <tr>
+ <td>Basic support</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatGeckoMobile(42)}}</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatNo}}</td>
+ </tr>
+ </tbody>
+</table>
+</div>
+
+<h2 id="相关连接">相关连接</h2>
+
+<ul>
+ <li>{{jsxref("Reflect")}}</li>
+ <li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/in"><code>in</code> operator</a></li>
+</ul>