这篇文章需要技术复核。如何帮忙。
我们的志愿者还没有将这篇文章翻译为 中文 (简体)。加入我们帮助完成翻译!
This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
The respondWith()
method of the FetchEvent
interface is intended for containing code that generates custom responses to the requests coming from the controlled page. This code will resolve by returning a Response
or network error to Fetch
.
Renderer-side security checks about tainting for cross-origin content are tied to the transparency (or opacity) of the Response
body, not URLs. If the request is a top-level navigation and the return value is a Response
whose type
attribute is opaque
(i.e. an opaque response body), a network error is returned to Fetch
. The final URL of all successful (non network-error) responses is the requested URL.
Syntax
FetchEvent.respondWith( //Promise that resolves to a Response or a network error. )
Returns
Void.
Parameters
Any custom response-generating code.
Examples
This code snippet is from the service worker fetch sample (run the fetch sample live.) The ServiceWorkerGlobalScope.onfetch
event handler listens for the fetch
event. When fired, FetchEvent.respondWith(any value)
returns a promise back to the controlled page. This promise resolves to the first matching URL request in the Cache
object. If no match is found, the code fetches a response from the network.
The code also handles exceptions thrown from the ServiceWorkerGlobalScope.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.
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; }).catch(function(error) { console.error('Fetching failed:', error); throw error; }); }) ); });
Specifications
Specification | Status | Comment |
---|---|---|
Service Workers The definition of 'respondWith()' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 40.0 | 44.0 (44.0)[1] | No support | 24 | No support |
Feature | Android | Android Webview | Firefox Mobile (Gecko) | Firefox OS | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|---|
Basic support | No support | ? | 44.0 (44.0) | (Yes) | No support | ? | No support | 44.0 |
[1] Service workers (and Push) have been disabled in the Firefox 45 Extended Support Release (ESR.)