copyResponse.js
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/*
Copyright 2019 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 { canConstructResponseFromBodyStream } from './_private/canConstructResponseFromBodyStream.js';
import './_version.js';
/**
* Allows developers to copy a response and modify its `headers`, `status`,
* or `statusText` values (the values settable via a
* [`ResponseInit`]{@link https://developer.mozilla.org/en-US/docs/Web/API/Response/Response#Syntax}
* object in the constructor).
* To modify these values, pass a function as the second argument. That
* function will be invoked with a single object with the response properties
* `{headers, status, statusText}`. The return value of this function will
* be used as the `ResponseInit` for the new `Response`. To change the values
* either modify the passed parameter(s) and return it, or return a totally
* new object.
*
* @param {Response} response
* @param {Function} modifier
* @memberof module:workbox-core
*/
async function copyResponse(response, modifier) {
const clonedResponse = response.clone();
// Create a fresh `ResponseInit` object by cloning the headers.
const responseInit = {
headers: new Headers(clonedResponse.headers),
status: clonedResponse.status,
statusText: clonedResponse.statusText,
};
// Apply any user modifications.
const modifiedResponseInit = modifier ? modifier(responseInit) : responseInit;
// Create the new response from the body stream and `ResponseInit`
// modifications. Note: not all browsers support the Response.body stream,
// so fall back to reading the entire body into memory as a blob.
const body = canConstructResponseFromBodyStream() ?
clonedResponse.body : await clonedResponse.blob();
return new Response(body, modifiedResponseInit);
}
export { copyResponse };