RangeRequestsPlugin.js
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/*
Copyright 2018 Google LLC
Use of this source code is governed by an MIT-style
license that can be found in the LICENSE file or at
https://opensource.org/licenses/MIT.
*/
import { createPartialResponse } from './createPartialResponse.js';
import './_version.js';
/**
* The range request plugin makes it easy for a request with a 'Range' header to
* be fulfilled by a cached response.
*
* It does this by intercepting the `cachedResponseWillBeUsed` plugin callback
* and returning the appropriate subset of the cached response body.
*
* @memberof module:workbox-range-requests
*/
class RangeRequestsPlugin {
constructor() {
/**
* @param {Object} options
* @param {Request} options.request The original request, which may or may not
* contain a Range: header.
* @param {Response} options.cachedResponse The complete cached response.
* @return {Promise<Response>} If request contains a 'Range' header, then a
* new response with status 206 whose body is a subset of `cachedResponse` is
* returned. Otherwise, `cachedResponse` is returned as-is.
*
* @private
*/
this.cachedResponseWillBeUsed = async ({ request, cachedResponse }) => {
// Only return a sliced response if there's something valid in the cache,
// and there's a Range: header in the request.
if (cachedResponse && request.headers.has('range')) {
return await createPartialResponse(request, cachedResponse);
}
// If there was no Range: header, or if cachedResponse wasn't valid, just
// pass it through as-is.
return cachedResponse;
};
}
}
export { RangeRequestsPlugin };