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68 lines
3.0 KiB
68 lines
3.0 KiB
/* |
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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.js'; |
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import { createHeaders } from './utils/createHeaders.js'; |
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import { concatenateToResponse } from './concatenateToResponse.js'; |
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import { isSupported } from './isSupported.js'; |
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import './_version.js'; |
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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 {Array<function({event, request, url, params})>} sourceFunctions |
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* An array of functions similar to {@link workbox-routing~handlerCallback} |
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* but that instead 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~handlerCallback} |
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* @memberof workbox-streams |
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*/ |
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function strategy(sourceFunctions, headersInit) { |
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return async ({ event, request, url, params }) => { |
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const sourcePromises = sourceFunctions.map((fn) => { |
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// Ensure the return value of the function is always a promise. |
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return Promise.resolve(fn({ event, request, url, params })); |
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}); |
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if (isSupported()) { |
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const { done, response } = concatenateToResponse(sourcePromises, headersInit); |
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if (event) { |
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event.waitUntil(done); |
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} |
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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 blobPartsPromises = sourcePromises.map(async (sourcePromise) => { |
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const source = await sourcePromise; |
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if (source instanceof Response) { |
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return source.blob(); |
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} |
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else { |
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// Technically, a `StreamSource` object can include any valid |
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// `BodyInit` type, including `FormData` and `URLSearchParams`, which |
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// cannot be passed to the Blob constructor directly, so we have to |
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// convert them to actual Blobs first. |
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return new Response(source).blob(); |
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} |
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}); |
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const blobParts = await Promise.all(blobPartsPromises); |
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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(blobParts), { headers }); |
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}; |
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} |
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export { strategy };
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