---
title: Client.postMessage()
slug: Web/API/Client/postMessage
translation_of: Web/API/Client/postMessage
---
<p>{{SeeCompatTable}}{{APIRef("Client")}}</p>

<p class="summary">{{domxref("Client")}} 接口的 <code><strong>Client.postMessage()</strong></code> 方法允许一个service worker客户端向一个  {{domxref("ServiceWorker")}}发送一个消息，会触发service worker的message事件，通过监听这个事件，可以获取这个消息。</p>

<h2 id="语法">语法</h2>

<pre class="brush: js">Client.postMessage(message[, transfer]);</pre>

<h3 id="返回">返回</h3>

<p>Void.</p>

<h3 id="参数">参数</h3>

<dl>
 <dt><code>message</code></dt>
 <dd>发送给service worker的消息内容。</dd>
 <dt><code>transfer {{optional_inline}}</code></dt>
 <dd>可转移的对象，例如对端口的引用。</dd>
</dl>

<h2 id="例子">例子</h2>

<p>从 service worker 向 client 发送消息：</p>

<pre class="brush: js line-numbers language-js"><code class="language-js"><span class="function token">addEventListener</span><span class="punctuation token">(</span><span class="string token">'fetch'</span><span class="punctuation token">,</span> <span class="parameter token">event</span> <span class="operator token">=&gt;</span> <span class="punctuation token">{</span>
  event<span class="punctuation token">.</span><span class="function token">waitUntil</span><span class="punctuation token">(</span><span class="keyword token">async</span> <span class="keyword token">function</span><span class="punctuation token">(</span><span class="punctuation token">)</span> <span class="punctuation token">{</span>
    <span class="comment token">// Exit early if we don't have access to the client.</span>
    <span class="comment token">// Eg, if it's cross-origin.</span>
    <span class="keyword token">if</span> <span class="punctuation token">(</span><span class="operator token">!</span>event<span class="punctuation token">.</span>clientId<span class="punctuation token">)</span> <span class="keyword token">return</span><span class="punctuation token">;</span>

    <span class="comment token">// Get the client.</span>
    <span class="keyword token">const</span> client <span class="operator token">=</span> <span class="keyword token">await</span> clients<span class="punctuation token">.</span><span class="function token">get</span><span class="punctuation token">(</span>event<span class="punctuation token">.</span>clientId<span class="punctuation token">)</span><span class="punctuation token">;</span>
    <span class="comment token">// Exit early if we don't get the client.</span>
    <span class="comment token">// Eg, if it closed.</span>
    <span class="keyword token">if</span> <span class="punctuation token">(</span><span class="operator token">!</span>client<span class="punctuation token">)</span> <span class="keyword token">return</span><span class="punctuation token">;</span>

    <span class="comment token">// Send a message to the client.</span>
    client<span class="punctuation token">.</span><span class="function token">postMessage</span><span class="punctuation token">(</span><span class="punctuation token">{</span>
      msg<span class="punctuation token">:</span> <span class="string token">"Hey I just got a fetch from you!"</span><span class="punctuation token">,</span>
      url<span class="punctuation token">:</span> event<span class="punctuation token">.</span>request<span class="punctuation token">.</span>url
    <span class="punctuation token">}</span><span class="punctuation token">)</span><span class="punctuation token">;</span>

  <span class="punctuation token">}</span><span class="punctuation token">(</span><span class="punctuation token">)</span><span class="punctuation token">)</span><span class="punctuation token">;</span>
<span class="punctuation token">}</span><span class="punctuation token">)</span><span class="punctuation token">;</span></code></pre>

<p><span class="punctuation token">接收message:</span></p>

<pre class="brush: js line-numbers language-js"><code class="language-js">navigator<span class="punctuation token">.</span>serviceWorker<span class="punctuation token">.</span><span class="function token">addEventListener</span><span class="punctuation token">(</span><span class="string token">'message'</span><span class="punctuation token">,</span> <span class="parameter token">event</span> <span class="operator token">=&gt;</span> <span class="punctuation token">{</span>
  console<span class="punctuation token">.</span><span class="function token">log</span><span class="punctuation token">(</span>event<span class="punctuation token">.</span>data<span class="punctuation token">.</span>msg<span class="punctuation token">,</span> event<span class="punctuation token">.</span>data<span class="punctuation token">.</span>url<span class="punctuation token">)</span><span class="punctuation token">;</span>
<span class="punctuation token">}</span><span class="punctuation token">)</span><span class="punctuation token">;</span></code> </pre>

<h2 id="Specifications">Specifications</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('Service Workers', '#client-postmessage-method', 'postMessage()')}}</td>
   <td>{{Spec2('Service Workers')}}</td>
   <td>Initial definition.</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<div>{{CompatibilityTable}}</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 (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatChrome(45.0)}}<sup>[1]</sup></td>
   <td>{{ CompatGeckoDesktop("44.0") }}<sup>[2]</sup></td>
   <td>{{CompatNo}}</td>
   <td>{{CompatUnknown}}</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>Android Webview</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Firefox OS</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
   <th>Chrome for Android</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{ CompatGeckoMobile("44.0") }}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatChrome(45.0)}} [1]</td>
  </tr>
 </tbody>
</table>
</div>

<ul>
 <li>[1] Behind a flag in Chrome 40 through 44.</li>
 <li>[2] Service workers (and <a href="/en-US/docs/Web/API/Push_API">Push</a>) have been disabled in the <a href="https://www.mozilla.org/en-US/firefox/organizations/">Firefox 45 &amp; 52 Extended Support Releases</a> (ESR.)</li>
</ul>