---
title: ServiceWorkerGlobalScope
slug: Web/API/ServiceWorkerGlobalScope
translation_of: Web/API/ServiceWorkerGlobalScope
---
<div>{{APIRef("Service Workers API")}}</div>

<p><a href="/en-US/docs/Web/API/ServiceWorker_API">ServiceWorker API</a> 的<code>ServiceWorkerGlobalScope</code> 接口，代表一个service worker的全局执行上下文。</p>

<p>开发者应该知道， ServiceWorker 的状态在结束/重启的循环中不是一直保持不变的，所以每个事件处理器应该设定一个默认的全局状态。</p>

<p>一旦成功地注册了service worker，为了节省内存和处理器，它将在他的状态达到了空闲的时候被终止。 一个在激活状态的service worker为了响应事件是可以自动重启的，就像这两个方法， {{domxref("ServiceWorkerGlobalScope.onfetch")}} 或者{{domxref("ServiceWorkerGlobalScope.onmessage")}}.</p>

<p>此外, 在service worker中, 同步请求是被禁止的 - 只有异步请求，如方法{{domxref("GlobalFetch.fetch", "fetch()")}} 才被允许.</p>

<p>该接口继承自 {{domxref("WorkerGlobalScope")}} 接口, 以及其父类 {{domxref("EventTarget")}}, 因此继承属性来自 {{domxref("WindowTimers")}}, {{domxref("WindowBase64")}}, 和 {{domxref("WindowEventHandlers")}}.</p>

<p>{{InheritanceDiagram(700, 85, 20)}}</p>

<h2 id="属性">属性</h2>

<dl>
 <dt>{{domxref("ServiceWorkerGlobalScope.clients")}} {{readonlyinline}}</dt>
 <dd>Contains the {{domxref("Clients")}} object associated with the service worker.</dd>
 <dt>{{domxref("ServiceWorkerGlobalScope.registration")}} {{readonlyinline}}</dt>
 <dd>Contains the {{domxref("ServiceWorkerRegistration")}} object that represents the service worker's registration.</dd>
 <dt>{{domxref("ServiceWorkerGlobalScope.caches")}} {{readonlyinline}}</dt>
 <dd>Contains the {{domxref("CacheStorage")}} object associated with the service worker.</dd>
</dl>

<h3 id="Event_handlers">Event handlers</h3>

<dl>
 <dt>{{domxref("ServiceWorkerGlobalScope.onactivate")}}</dt>
 <dd>An event handler fired whenever an {{Event("activate")}} event occurs — when a {{domxref("ServiceWorkerRegistration")}} acquires a new {{domxref("ServiceWorkerRegistration.active")}} worker.</dd>
 <dt>{{domxref("ServiceWorkerGlobalScope.onfetch")}}</dt>
 <dd>An event handler fired whenever a {{Event("fetch")}} event occurs — when a {{domxref("GlobalFetch.fetch", "fetch()")}} is called.</dd>
 <dt>{{domxref("ServiceWorkerGlobalScope.oninstall")}}</dt>
 <dd>An event handler fired whenever an {{Event("install")}} event occurs — when a {{domxref("ServiceWorkerRegistration")}} acquires a new {{domxref("ServiceWorkerRegistration.installing")}} worker.</dd>
 <dt>{{domxref("ServiceWorkerGlobalScope.onmessage")}}</dt>
 <dd>An event handler fired whenever a {{Event("message")}} event occurs — when incoming messages are received. Controlled pages can use the {{domxref("MessagePort.postMessage()")}} method to send messages to service workers. The service worker can optionally send a response back via the {{domxref("MessagePort")}} exposed in <a href="https://html.spec.whatwg.org/multipage/comms.html#messageport"><code>event.data.port</code></a>, corresponding to the controlled page.</dd>
 <dt>{{domxref("ServiceWorkerGlobalScope.onnotificationclick")}}</dt>
 <dd>An event handler fired whenever a {{Event("notificationclick")}} event occurs — when a user clicks on a displayed notification.</dd>
 <dt>{{domxref("ServiceWorkerGlobalScope.onnotificationclose")}}</dt>
 <dd>An event handler fired whenever a {{Event("notificationclose")}} event occurs — when a user closes a displayed notification.</dd>
 <dt>{{domxref("ServiceWorkerGlobalScope.onpush")}}</dt>
 <dd>An event handler fired whenever a {{Event("push")}} event occurs — when a server push notification is received.</dd>
 <dt>{{domxref("ServiceWorkerGlobalScope.onpushsubscriptionchange")}}</dt>
 <dd>An event handler fired whenever a {{Event("pushsubscriptionchange")}} event occurs — when a push subscription has been invalidated, or is about to be invalidated (e.g. when a push service sets an expiration time.)</dd>
 <dt>{{domxref("ServiceWorkerGlobalScope.onsync")}}</dt>
 <dd>An event handler fired whenever a {{Event("SyncEvent")}} event occurs. This is triggered when a call to {{domxref("SyncManager.register")}} is made from a service worker client page. The attempt to sync is made either immediately if the network is available or as soon as the network becomes available. </dd>
</dl>

<h2 id="方法">方法</h2>

<dl>
 <dt>{{domxref("ServiceWorkerGlobalScope.skipWaiting()")}}</dt>
 <dd>Allows the current service worker registration to progress from waiting to active state while service worker clients are using it.</dd>
</dl>

<p><code>ServiceWorkerGlobalScope</code> implements {{domxref("WorkerGlobalScope")}} — which implements {{domxref("GlobalFetch")}}. Therefore it also has the following property available to it:</p>

<dl>
 <dt>{{domxref("GlobalFetch.fetch()")}}</dt>
 <dd>Starts the process of fetching a resource. This returns a promise that resolves to the {{domxref("Response")}} object representing the response to your request. This algorithm is the entry point for the fetch handling handed to the service worker context.</dd>
</dl>

<h2 id="示例">示例</h2>

<p>This code snippet is from the <a href="https://github.com/GoogleChrome/samples/blob/gh-pages/service-worker/prefetch/service-worker.js">service worker prefetch sample</a> (see <a href="https://googlechrome.github.io/samples/service-worker/prefetch/">prefetch example live</a>.) The {{domxref("ServiceWorkerGlobalScope.onfetch")}} event handler listens for the <code>fetch</code> event. When fired, the code returns a promise that resolves to the first matching request in the {{domxref("Cache")}} object. If no match is found, the code fetches a response from the network.</p>

<p>The code also handles exceptions thrown from the {{domxref("GlobalFetch.fetch", "fetch()")}} operation. Note that an HTTP error response (e.g., 404) will not trigger an exception. It will return a normal response object that has the appropriate error code set.</p>

<pre class="brush: js notranslate">self.addEventListener('fetch', function(event) {
  console.log('Handling fetch event for', event.request.url);

  event.respondWith(
    caches.match(event.request).then(function(response) {
      if (response) {
        console.log('Found response in cache:', response);

        return response;
      }
      console.log('No response found in cache. About to fetch from network...');

      return fetch(event.request).then(function(response) {
        console.log('Response from network is:', response);

        return response;
      }, function(error) {
        console.error('Fetching failed:', error);

        throw error;
      });
    })
  );
});</pre>

<h2 id="规范">规范</h2>

<table class="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>{{SpecName('Service Workers', '#service-worker-global-scope', 'ServiceWorkerGlobalScope')}}</td>
   <td>{{Spec2('Service Workers')}}</td>
   <td>Initial definition</td>
  </tr>
  <tr>
   <td>{{SpecName('Fetch', '#concept-fetch', 'Fetch')}}</td>
   <td>{{Spec2('Fetch')}}</td>
   <td>Adds the {{domxref("ServiceWorkerGlobalScope.fetch", "fetch")}} method.</td>
  </tr>
  <tr>
   <td>{{SpecName('Push API', '#widl-ServiceWorkerGlobalScope-onpush', 'onpush')}}</td>
   <td>{{Spec2('Push API')}}</td>
   <td>Adds the {{domxref("ServiceWorkerGlobalScope.onpush", "onpush")}} and {{domxref("ServiceWorkerGlobalScope.onpushsubscriptionchange", "onpushsubscriptionchange")}} event handlers.</td>
  </tr>
  <tr>
   <td>{{SpecName('Web Notifications','#dom-serviceworkerglobalscope-onnotificationclick','onnotificationclick')}}</td>
   <td>{{Spec2('Web Notifications')}}</td>
   <td>Adds the {{domxref("ServiceWorkerGlobalScope.onnotificationclick", "onnotificationclick")}} event handler.</td>
  </tr>
  <tr>
   <td>{{SpecName('Background Sync','#sync-event','onsync')}}</td>
   <td>{{Spec2('Background Sync')}}</td>
   <td>Adds the {{domxref("ServiceWorkerGlobalScope.onsync","onsync")}} event.</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

{{Compat("api.ServiceWorkerGlobalScope")}}

<h2 id="See_also">See also</h2>

<ul>
 <li><a href="/en-US/docs/Web/API/ServiceWorker_API/Using_Service_Workers">Using Service Workers</a></li>
 <li><a class="external external-icon" href="https://github.com/mdn/sw-test">Service workers basic code example</a></li>
 <li><a class="external external-icon" href="https://jakearchibald.github.io/isserviceworkerready/">Is ServiceWorker ready?</a></li>
 <li>{{jsxref("Promise")}}</li>
 <li><a href="/en-US/docs/Web/Guide/Performance/Using_web_workers">Using web workers</a></li>
</ul>