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author | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
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committer | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
commit | 33058f2b292b3a581333bdfb21b8f671898c5060 (patch) | |
tree | 51c3e392513ec574331b2d3f85c394445ea803c6 /files/zh-cn/web/javascript/reference/global_objects/reflect/getownpropertydescriptor | |
parent | 8b66d724f7caf0157093fb09cfec8fbd0c6ad50a (diff) | |
download | translated-content-33058f2b292b3a581333bdfb21b8f671898c5060.tar.gz translated-content-33058f2b292b3a581333bdfb21b8f671898c5060.tar.bz2 translated-content-33058f2b292b3a581333bdfb21b8f671898c5060.zip |
initial commit
Diffstat (limited to 'files/zh-cn/web/javascript/reference/global_objects/reflect/getownpropertydescriptor')
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diff --git a/files/zh-cn/web/javascript/reference/global_objects/reflect/getownpropertydescriptor/index.html b/files/zh-cn/web/javascript/reference/global_objects/reflect/getownpropertydescriptor/index.html new file mode 100644 index 0000000000..e999254e32 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/reflect/getownpropertydescriptor/index.html @@ -0,0 +1,139 @@ +--- +title: Reflect.getOwnPropertyDescriptor() +slug: Web/JavaScript/Reference/Global_Objects/Reflect/getOwnPropertyDescriptor +translation_of: Web/JavaScript/Reference/Global_Objects/Reflect/getOwnPropertyDescriptor +--- +<div>{{JSRef}}</div> + +<p>静态方法 <code><strong>Reflect</strong></code><strong><code>.getOwnPropertyDescriptor()</code></strong> 与 {{jsxref("Object.getOwnPropertyDescriptor()")}} 方法相似。如果在对象中存在,则返回给定的属性的属性描述符。否则返回 {{jsxref("undefined")}}。 </p> + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox">Reflect.getOwnPropertyDescriptor(target, propertyKey) +</pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>target</code></dt> + <dd>需要寻找属性的目标对象。</dd> + <dt><code>propertyKey</code></dt> + <dd>获取自己的属性描述符的属性的名称。</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>如果属性存在于给定的目标对象中,则返回属性描述符;否则,返回 {{jsxref("undefined")}}。</p> + +<h3 id="异常">异常</h3> + +<p>抛出一个 {{jsxref("TypeError")}},如果目标不是 {{jsxref("Object")}}。</p> + +<h2 id="描述">描述</h2> + +<p><code>Reflect.getOwnPropertyDescriptor</code>方法返回一个属性描述符,如果给定的属性存在于对象中,否则返回 {{jsxref("undefined")}} 。 与 {{jsxref("Object.getOwnPropertyDescriptor()")}} 的唯一不同在于如何处理非对象目标。</p> + +<h2 id="示例">示例</h2> + +<h3 id="使用_Reflect.getOwnPropertyDescriptor()">使用 <code>Reflect.getOwnPropertyDescriptor()</code></h3> + +<pre class="brush: js">Reflect.getOwnPropertyDescriptor({x: "hello"}, "x"); +// {value: "hello", writable: true, enumerable: true, configurable: true} + +Reflect.getOwnPropertyDescriptor({x: "hello"}, "y"); +// undefined + +Reflect.getOwnPropertyDescriptor([], "length"); +// {value: 0, writable: true, enumerable: false, configurable: false} +</pre> + +<h3 id="与_Object.getOwnPropertyDescriptor()_的不同点">与 <code>Object.getOwnPropertyDescriptor() 的不同点</code></h3> + +<p>如果该方法的第一个参数不是一个对象(一个原始值),那么将造成 {{jsxref("TypeError")}} 错误。而对于 {{jsxref("Object.getOwnPropertyDescriptor")}},非对象的第一个参数将被强制转换为一个对象处理。</p> + +<pre class="brush: js">Reflect.getOwnPropertyDescriptor("foo", 0); +// TypeError: "foo" is not non-null object + +Object.getOwnPropertyDescriptor("foo", 0); +// { value: "f", writable: false, enumerable: true, configurable: 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.getownpropertydescriptor', 'Reflect.getOwnPropertyDescriptor')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-reflect.getownpropertydescriptor', 'Reflect.getOwnPropertyDescriptor')}}</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>10</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>49</td> + <td>{{CompatGeckoMobile(42)}}</td> + <td>{{CompatNo}}</td> + <td>{{CompatNo}}</td> + <td>10</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="相关链接">相关链接</h2> + +<ul> + <li>{{jsxref("Reflect")}}</li> + <li>{{jsxref("Object.getOwnPropertyDescriptor()")}}</li> +</ul> |