uTools-Manuals/docs/javascript/Reference/Global_Objects/Object/__lookupSetter__.html

<article id="wikiArticle">
<div> <div class="blockIndicator deprecated deprecatedHeader">
<p><strong><span class="icon-only-inline" title="This is an obsolete API and is no longer guaranteed to work."><i class="icon-trash"> </i></span> 已废弃</strong><br/>该特性已经从 Web 标准中删除，虽然一些浏览器目前仍然支持它，但也许会在未来的某个时间停止支持，请尽量不要使用该特性。</p>
</div></div>
<div><code><strong>__lookupSetter__</strong></code> 方法是用来返回一个对象的某个属性上绑定了 setter （设置器）的钩子函数的引用。</div>
<div> </div>
<h2 id="语法">语法</h2>
<pre><code class="language-javascript"><code><var>obj</var>.__lookupSetter__(<var>sprop</var>)</code></code></pre>
<h3 id="参数说明">参数说明</h3>
<dl>
<dt><code>sprop</code></dt>
<dd>一个字符串类型，表示要返回的 setter 钩子的函数名。</dd>
</dl>
<h3 id="返回值">返回值</h3>
<p>一个绑定了setter的特殊属性的函数引用。</p>
<h2 id="描述">描述</h2>
<p>如果一个 setter 被定义在了一个对象的属性上，则不能直接通过该属性来获取引用 setter 所设置的钩子的函数，因为该属性是该函数的返回值，但，__lookupSetter__ 可以被用来获取对 setter 函数的引用。</p>
<p>不过现在可以使用标准的方法：</p>
<p><a href="Reference/Global_Objects/Object/getOwnPropertyDescriptor" title="Object.getOwnPropertyDescriptor() 方法返回指定对象上一个自有属性对应的属性描述符。（自有属性指的是直接赋予该对象的属性，不需要从原型链上进行查找的属性）"><code>Object.getOwnPropertyDescriptor()</code></a>.</p>
<h2 id="示例">示例</h2>
<pre><code  class="language-javascript">var obj = {
  set foo(value) {
    this.bar = value;
  }
};


// 非标准，并且不推荐使用。
obj.__lookupSetter__('foo')
// (function(value) { this.bar = value; })


// 标准且推荐使用的方式。
Object.getOwnPropertyDescriptor(obj, 'foo').set;
// (function(value) { this.bar = value; })
</code></pre>
<h2 id="规范">规范</h2>
<table class="spectable standard-table">
<tbody>
<tr>
<th scope="col">规范</th>
<th scope="col">状态</th>
<th scope="col">备注</th>
</tr>
<tr>
<td><a class="external" href="https://tc39.github.io/ecma262/#sec-object.prototype.__lookupSetter__" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">Object.prototype.__lookupSetter__()</small></a></td>
<td><span class="spec-Draft">Draft</span></td>
<td>包含在（规范性）附件中，用于Web浏览器的附加ECMAScript遗留功能（请注意，这份规范编撰的内容已经是准备实现的了）。</td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
<div><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>.
            This compatibility table still uses the old format,
            because we haven't yet converted the data it contains.
            <strong><a class="new" href="/zh-CN/docs/MDN/Contribute/Structures/Compatibility_tables" rel="nofollow">Find out how you can help!</a></strong></div>
<div class="htab">
<a id="AutoCompatibilityTable" name="AutoCompatibilityTable"></a>
<ul>
<li class="selected"><a>Desktop</a></li>
<li><a>Mobile</a></li>
</ul>
</div></div>
<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><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
<td>11</td>
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></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><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
<td><span style="color: rgb(255, 153, 0);" title="Compatibility unknown; please update this.">?</span></td>
<td><span style="color: rgb(255, 153, 0);" title="Compatibility unknown; please update this.">?</span></td>
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
</tr>
</tbody>
</table>
</div>
<h2 id="相关链接">相关链接</h2>
<ul>
<li><a href="Reference/Global_Objects/Object/__lookupGetter__" title="__lookupGetter__ 方法会返回当前对象上指定属性的属性读取访问器函数（getter）。"><code>Object.prototype.__lookupGetter__()</code></a></li>
<li><a href="Reference/Functions/set" title="当尝试设置属性时，set语法将对象属性绑定到要调用的函数。"><code>set</code></a> operator</li>
<li><a href="Reference/Global_Objects/Object/getOwnPropertyDescriptor" title="Object.getOwnPropertyDescriptor() 方法返回指定对象上一个自有属性对应的属性描述符。（自有属性指的是直接赋予该对象的属性，不需要从原型链上进行查找的属性）"><code>Object.getOwnPropertyDescriptor()</code></a> and <a href="Reference/Global_Objects/Object/getPrototypeOf" title="Object.getPrototypeOf() 方法返回指定对象的原型（内部[[Prototype]]属性的值）。"><code>Object.getPrototypeOf()</code></a></li>
<li><a href="Reference/Global_Objects/Object/__defineGetter__" title="__defineGetter__ 方法可以将一个函数绑定在当前对象的指定属性上，当那个属性的值被读取时，你所绑定的函数就会被调用。"><code>Object.prototype.__defineGetter__()</code></a></li>
<li><a href="Reference/Global_Objects/Object/__defineSetter__" title="__defineSetter__ 方法可以将一个函数绑定在当前对象的指定属性上，当那个属性被赋值时，你所绑定的函数就会被调用。"><code>Object.prototype.__defineSetter__()</code></a></li>
<li><a href="/en-US/docs/Web/JavaScript/Guide/Working_with_Objects#Defining_getters_and_setters">JS Guide: Defining Getters and Setters</a></li>
</ul>
</article>