71 lines
2.5 KiB
JavaScript
71 lines
2.5 KiB
JavaScript
/*
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Copyright 2018 Google LLC
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Use of this source code is governed by an MIT-style
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license that can be found in the LICENSE file or at
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https://opensource.org/licenses/MIT.
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*/
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import {logger} from 'workbox-core/_private/logger.mjs';
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import {createHeaders} from './utils/createHeaders.mjs';
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import {concatenateToResponse} from './concatenateToResponse.mjs';
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import {isSupported} from './isSupported.mjs';
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import './_version.mjs';
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/**
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* A shortcut to create a strategy that could be dropped-in to Workbox's router.
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*
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* On browsers that do not support constructing new `ReadableStream`s, this
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* strategy will automatically wait for all the `sourceFunctions` to complete,
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* and create a final response that concatenates their values together.
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*
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* @param {
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* Array<function(workbox.routing.Route~handlerCallback)>} sourceFunctions
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* Each function should return a {@link workbox.streams.StreamSource} (or a
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* Promise which resolves to one).
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* @param {HeadersInit} [headersInit] If there's no `Content-Type` specified,
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* `'text/html'` will be used by default.
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* @return {workbox.routing.Route~handlerCallback}
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*
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* @memberof workbox.streams
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*/
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export function strategy(sourceFunctions, headersInit) {
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return async ({event, url, params}) => {
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if (isSupported()) {
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const {done, response} = concatenateToResponse(sourceFunctions.map(
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(fn) => fn({event, url, params})), headersInit);
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event.waitUntil(done);
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return response;
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}
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if (process.env.NODE_ENV !== 'production') {
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logger.log(`The current browser doesn't support creating response ` +
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`streams. Falling back to non-streaming response instead.`);
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}
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// Fallback to waiting for everything to finish, and concatenating the
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// responses.
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const parts = await Promise.all(
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sourceFunctions.map(
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(sourceFunction) => sourceFunction({event, url, params})
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).map(async (responsePromise) => {
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const response = await responsePromise;
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if (response instanceof Response) {
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return response.blob();
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}
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// Otherwise, assume it's something like a string which can be used
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// as-is when constructing the final composite blob.
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return response;
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})
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);
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const headers = createHeaders(headersInit);
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// Constructing a new Response from a Blob source is well-supported.
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// So is constructing a new Blob from multiple source Blobs or strings.
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return new Response(new Blob(parts), {headers});
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};
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}
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