---
title: PushManager.getSubscription()
slug: Web/API/PushManager/getSubscription
tags:
  - API
  - PushManager
  - Service Worker
  - 实验中的
  - 方法
translation_of: Web/API/PushManager/getSubscription
---
<p>{{SeeCompatTable}}{{ApiRef("Push API")}}</p>

<p>{{domxref("PushManager")}} 接口的方法<strong><code>PushManager.getSubscription()</code></strong> 尝试获取已有的推送订阅。</p>

<p>它返回一个 {{jsxref("Promise")}} 用来resolve出一个包含现有订阅的详细信息的{{domxref("PushSubscription")}} 对象。如果不存在已有的推送订阅，返回null。</p>

<h2 id="语法">语法</h2>

<pre class="brush: js notranslate" style="font-size: 14px;">​PushManager.getSubscription().then(function(pushSubscription) { ... } );</pre>

<h3 id="参数">参数</h3>

<p>无。</p>

<h3 id="返回值">返回值</h3>

<p>A {{jsxref("Promise")}} that resolves to a {{domxref("PushSubscription")}} object or <code>null</code>.</p>

<h2 id="例子">例子</h2>

<p>这个代码片段来自 <a href="https://github.com/GoogleChrome/samples/blob/gh-pages/push-messaging-and-notifications">push messaging and notification sample</a>. (没有能直接运行的例子.)</p>

<pre class="brush: js notranslate" style="font-size: 14px;">// We need the service worker registration to check for a subscription
  navigator.serviceWorker.ready.then(function(serviceWorkerRegistration) {
    // Do we already have a push message subscription?
    serviceWorkerRegistration.pushManager.getSubscription()
      .then(function(subscription) {
        // Enable any UI which subscribes / unsubscribes from
        // push messages.
        var pushButton = document.querySelector('.js-push-button');
        pushButton.disabled = false;

        if (!subscription) {
          // We aren’t subscribed to push, so set UI
          // to allow the user to enable push
          return;
        }

        // Keep your server in sync with the latest subscriptionId
        sendSubscriptionToServer(subscription);

        showCurlCommand(subscription);

        // Set your UI to show they have subscribed for
        // push messages
        pushButton.textContent = 'Disable Push Messages';
        isPushEnabled = true;
      })
      .catch(function(err) {
        window.Demo.debug.log('Error during getSubscription()', err);
      });
  });
</pre>

<h2 id="说明">说明</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">说明</th>
   <th scope="col">状态</th>
   <th scope="col">注释</th>
  </tr>
  <tr>
   <td>{{SpecName('Push API', '#widl-PushManager-getSubscription-Promise-PushSubscription', 'getSubscription()')}}</td>
   <td>{{Spec2('Push API')}}</td>
   <td>最初的定义</td>
  </tr>
 </tbody>
</table>

<h2 id="支持的浏览器">支持的浏览器</h2>

<div>
<div>
<div class="hidden">这个支持的浏览器列表是由结构化数据生成的。如果你想修改这个表格，请获取最新的代码并提交t<a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> 。</div>

<p>{{Compat("api.PushManager.getSubscription")}}</p>
</div>
</div>

<div id="gtx-trans" style="position: absolute; left: 488px; top: 144px;">
<div class="gtx-trans-icon"></div>
</div>