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authorPeter Bengtsson <mail@peterbe.com>2020-12-08 14:40:17 -0500
committerPeter Bengtsson <mail@peterbe.com>2020-12-08 14:40:17 -0500
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+---
+title: handler.set()
+slug: Web/JavaScript/Reference/Global_Objects/Proxy/handler/set
+tags:
+ - ECMAScript6
+ - JavaScript
+ - Method
+ - Proxy
+ - Proxy拦截
+translation_of: Web/JavaScript/Reference/Global_Objects/Proxy/Proxy/set
+---
+<div>{{JSRef}}</div>
+
+<p><code><strong>handler.set()</strong></code> 方法是设置属性值操作的捕获器。</p>
+
+<div>{{EmbedInteractiveExample("pages/js/proxyhandler-set.html", "taller")}}</div>
+
+
+
+<h2 id="语法">语法</h2>
+
+<pre class="syntaxbox">const <var>p</var> = new Proxy(<var>target</var>, {
+ set: function(<var>target</var>, <var>property</var>, <var>value</var>, <var>receiver</var>) {
+ }
+});
+</pre>
+
+<h3 id="参数">参数</h3>
+
+<p>以下是传递给 <code>set()</code> 方法的参数。<code>this</code> 绑定在 handler 对象上。</p>
+
+<dl>
+ <dt><code><var>target</var></code></dt>
+ <dd>目标对象。</dd>
+ <dt><code><var>property</var></code></dt>
+ <dd>将被设置的属性名或 {{jsxref("Symbol")}}。</dd>
+ <dt><code><var>value</var></code></dt>
+ <dd>新属性值。</dd>
+ <dt><code><var>receiver</var></code></dt>
+ <dd>最初被调用的对象。通常是 proxy 本身,但 handler 的 set 方法也有可能在原型链上,或以其他方式被间接地调用(因此不一定是 proxy 本身)。
+ <div class="note">
+ <p><strong>比如:</strong>假设有一段代码执行 <code>obj.name = "jen"</code>, <code><var>obj</var></code> 不是一个 proxy,且自身不含 <code>name</code> 属性,但是它的原型链上有一个 proxy,那么,那个 proxy 的 <code>set()</code> 处理器会被调用,而此时,<code><var>obj</var></code> 会作为 receiver 参数传进来。</p>
+ </div>
+ </dd>
+</dl>
+
+<h3 id="返回值">返回值</h3>
+
+<p><code>set()</code> 方法应当返回一个布尔值。</p>
+
+<ul>
+ <li>返回 <code>true</code> 代表属性设置成功。</li>
+ <li>在严格模式下,如果 <code>set()</code> 方法返回 <code>false</code>,那么会抛出一个 {{jsxref("TypeError")}} 异常。</li>
+</ul>
+
+<h2 id="描述">描述</h2>
+
+<p><code>handler.set()</code> 方法用于拦截设置属性值的操作。</p>
+
+<h3 id="拦截">拦截</h3>
+
+<p>该方法会拦截目标对象的以下操作:</p>
+
+<ul>
+ <li>指定属性值:<code>proxy[foo] = bar</code> 和 <code>proxy.foo = bar</code></li>
+ <li>指定继承者的属性值:<code>Object.create(proxy)[foo] = bar</code></li>
+ <li>{{jsxref("Reflect.set()")}}</li>
+</ul>
+
+<h3 id="约束">约束</h3>
+
+<p>如果违背以下的约束条件,proxy 会抛出一个 {{jsxref("TypeError")}} 异常:</p>
+
+<ul>
+ <li>若目标属性是一个不可写及不可配置的数据属性,则不能改变它的值。</li>
+ <li>如果目标属性没有配置存储方法,即 <code>[[Set]]</code> 属性的是 <code>undefined</code>,则不能设置它的值。</li>
+ <li>在严格模式下,如果 <code>set()</code> 方法返回 <code>false</code>,那么也会抛出一个 {{jsxref("TypeError")}} 异常。</li>
+</ul>
+
+<h2 id="示例">示例</h2>
+
+<p>以下代码演示如何捕获属性的设置操作。</p>
+
+<pre class="brush: js">var p = new Proxy({}, {
+ set: function(target, prop, value, receiver) {
+ target[prop] = value;
+ console.log('property set: ' + prop + ' = ' + value);
+ return true;
+ }
+})
+
+console.log('a' in p); // false
+
+p.a = 10; // "property set: a = 10"
+console.log('a' in p); // true
+console.log(p.a); // 10</pre>
+
+<h2 id="规范">规范</h2>
+
+<table class="standard-table">
+ <thead>
+ <tr>
+ <th scope="col">规范</th>
+ </tr>
+ </thead>
+ <tbody>
+ <tr>
+ <td>{{SpecName('ESDraft', '#sec-proxy-object-internal-methods-and-internal-slots-set-p-v-receiver', '[[Set]]')}}</td>
+ </tr>
+ </tbody>
+</table>
+
+<h2 id="浏览器兼容性">浏览器兼容性</h2>
+
+
+
+<p>{{Compat("javascript.builtins.Proxy.handler.set")}}</p>
+
+<h2 id="另见">另见</h2>
+
+<ul>
+ <li>{{jsxref("Proxy")}}</li>
+ <li>{{jsxref("Proxy.handler", "handler")}}</li>
+ <li>{{jsxref("Reflect.set()")}}</li>
+</ul>