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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

preloadResponse 只读特性在 FetchEvent interface returns a Promise that resolves to the navigation preload 响应 if navigation preload was triggered or undefined otherwise.

句法

var expectedResponse = fetchEvent.preloadResponse;
					

值

A Promise 解析为 响应 or otherwise to undefined .

范例

This code snippet is from the navigation preload page 。 ServiceWorkerGlobalScope.onfetch event handler listens for the fetch event. When fired, pass a promise that back to the controlled page to FetchEvent.respondWith() . This promise resolves to the first matching URL request in the 缓存 object. If no match is found, the code checks for a preloaded response. Else it fetches a response from the network.

addEventListener('fetch', event => {
  event.respondWith(async function() {
    // Respond from the cache if we can
    const cachedResponse = await caches.match(event.request);
    if (cachedResponse) return cachedResponse;
    // Else, use the preloaded response, if it's there
    const response = await event.preloadResponse;
    if (response) return response;
    // Else try the network.
    return fetch(event.request);
  }());
});
					

规范

规范	状态	注释
服务工作者 The definition of 'preloadResponse' in that specification.	工作草案	初始定义。

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
preloadResponse	Chrome 59	Edge 18	Firefox ?	IE 不支持 No	Opera 46	Safari 不支持 No	WebView Android 59	Chrome Android 59	Firefox Android ?	Opera Android 43	Safari iOS 不支持 No	Samsung Internet Android 7.0

图例

完整支持

完整支持

不支持

不支持

兼容性未知 ?

兼容性未知

实验。期望将来行为有所改变。

实验。期望将来行为有所改变。

另请参阅

• 使用服务工作者
• 服务工作者基本代码范例
• ServiceWorker 就绪了吗？
• Promise
• Using web workers

元数据

• 最后修改： Jul 7, 2020

相关话题

1. 服务工作者 API
2. FetchEvent
3. 构造函数

   1. FetchEvent()
4. 特性

   1. client
   2. clientId
   3. isReload
   4. navigationPreload
   5. PreloadRequest
   6. preloadResponse
   7. replacesClientId
   8. request
   9. resultingClientId
5. 方法

   1. respondWith()
6. 继承：

   1. 事件
7. Related pages for Service Workers API

   1. 缓存
   2. CacheStorage
   3. Client
   4. Clients
   5. ExtendableEvent
   6. InstallEvent
   7. Navigator.serviceWorker
   8. NotificationEvent
   9. PeriodicSyncEvent
   10. PeriodicSyncManager
   11. PeriodicSyncRegistration
   12. ServiceWorker
   13. ServiceWorkerContainer
   14. ServiceWorkerGlobalScope
   15. ServiceWorkerRegistration
   16. SyncEvent
   17. SyncManager
   18. SyncRegistration
   19. WindowClient