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---
title: InstallEvent
slug: Web/API/InstallEvent
translation_of: Web/API/InstallEvent
---
<div>{{APIRef("Service Workers API")}}{{SeeCompatTable}}</div>
<p>该参数传递到 {{domxref("ServiceWorkerGlobalScope.oninstall", "oninstall")}} 事件处理程序，<code>InstallEvent接口表示一个 </code>{{domxref("ServiceWorker")}}<code> </code>的 {{domxref("ServiceWorkerGlobalScope")}} 上分派的安装操作。作为 {{domxref("ExtendableEvent")}} 的一个子类，它确保在安装期间不调度诸如 {{domxref("FetchEvent")}} 之类的功能事件。</p>
<p>该接口继承自 {{domxref("ExtendableEvent")}} 接口。</p>
<p>{{InheritanceDiagram(700, 60, 20)}}</p>
<h2 id="构造函数">构造函数</h2>
<dl>
<dt>{{domxref("InstallEvent.InstallEvent()")}}</dt>
<dd>创建一个新的<code>InstallEvent对象。</code></dd>
</dl>
<h2 id="属性">属性</h2>
<p><em>从它的祖先{{domxref("Event")}}继承属性。</em></p>
<dl>
<dt>{{domxref("InstallEvent.activeWorker")}} {{readonlyInline}}</dt>
<dd>返回当前处于激活状态，控制页面的{{domxref("ServiceWorker")}}。</dd>
</dl>
<h2 id="方法">方法</h2>
<p><em>从它的父类{{domxref("ExtendableEvent")}}继承方法。</em></p>
<h2 id="示例">示例</h2>
<p>该代码片段来自 <a href="https://github.com/GoogleChrome/samples/blob/gh-pages/service-worker/prefetch/service-worker.js">service worker prefetch sample</a> (请参阅 <a href="https://googlechrome.github.io/samples/service-worker/prefetch/">prefetch running live</a>)。代码在{{domxref("ServiceWorkerGlobalScope.oninstall")}}中调用{{domxref("ExtendableEvent.waitUntil", "ExtendableEvent.waitUntil(any value)")}}，并延迟将{{domxref("ServiceWorkerRegistration.installing")}} worker视为已安装的，直到传递的promise被成功地resolve。当所有资源已经获取并缓存，或者有任何异常发生时，promise才会resolve。</p>
<p>该代码片段也展示了服务工作线程使用的缓存版本控制的最佳实践。虽然此示例只有一个缓存，但您可以将此方法用于多个缓存。 代码将缓存的速记标识映射到特定的版本化缓存名称。</p>
<div class="note">
<p><strong>注意</strong>: service worker的注册日志记录在Chrome浏览器中可以通过访问chrome://serviceworker-internals查看。</p>
</div>
<pre class="brush: js">var CACHE_VERSION = 1;
var CURRENT_CACHES = {
prefetch: 'prefetch-cache-v' + CACHE_VERSION
};
self.addEventListener('install', function(event) {
var urlsToPrefetch = [
'./static/pre_fetched.txt',
'./static/pre_fetched.html',
'https://www.chromium.org/_/rsrc/1302286216006/config/customLogo.gif'
];
console.log('Handling install event. Resources to pre-fetch:', urlsToPrefetch);
event.waitUntil(
caches.open(CURRENT_CACHES['prefetch']).then(function(cache) {
cache.addAll(urlsToPrefetch.map(function(urlToPrefetch) {
return new Request(urlToPrefetch, {mode: 'no-cors'});
})).then(function() {
console.log('All resources have been fetched and cached.');
});
}).catch(function(error) {
console.error('Pre-fetching failed:', error);
})
);
});</pre>
<h2 id="规范">规范</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')}}</td>
<td>{{Spec2('Service Workers')}}</td>
<td>As of May 2015, the install event is an instance of {{domxref("ExtendableEvent")}} rather than a child of it.</td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
{{Compat("api.InstallEvent")}}
<h2 id="参见">参见</h2>
<ul>
<li>{{domxref("NotificationEvent")}}</li>
<li>{{jsxref("Promise")}}</li>
<li><a href="/en-US/docs/Web/API/Fetch_API">Fetch API</a></li>
</ul>
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