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diff --git a/files/zh-cn/web/javascript/reference/global_objects/reflect/has/index.html b/files/zh-cn/web/javascript/reference/global_objects/reflect/has/index.html new file mode 100644 index 0000000000..aaf55532e3 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/reflect/has/index.html @@ -0,0 +1,133 @@ +--- +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> |