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Simplify the ReadableStream polyfill

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At this point in time, all of the supported browsers (in the PDF.js project) have native `ReadableStream` implementations; see https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream#browser_compatibility

Hence the polyfill is *only* necessary in Node.js environments now, and we shouldn't need to do any detailed feature detection either (since that was only done for the non-Chromium versions of the MS Edge browser).
Finally, we can slightly reduce the size of the Chromium-extension since the polyfill shouldn't be needed there either.
This commit is contained in:
Jonas Jenwald 2021-08-13 12:26:54 +02:00
parent 14a0d612c4
commit e2aa067603
1 changed files with 7 additions and 18 deletions
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25
src/shared/compatibility.js
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@ -20,8 +20,8 @@ if (
(typeof PDFJSDev === "undefined" || !PDFJSDev.test("SKIP_BABEL")) &&
(typeof globalThis === "undefined" || !globalThis._pdfjsCompatibilityChecked)
) {
// Provides support for globalThis in legacy browsers.
// Support: Firefox<65, Chrome<71, Safari<12.1
// Provides support for `globalThis` in legacy browsers.
// Support: Firefox<65, Chrome<71, Safari<12.1, Node.js<12.0.0
if (typeof globalThis === "undefined" || globalThis.Math !== Math) {
// eslint-disable-next-line no-global-assign
globalThis = require("core-js/es/global-this");
@ -89,23 +89,12 @@ if (
// shouldn't need to be polyfilled for the IMAGE_DECODERS build target.
return;
}
let isReadableStreamSupported = false;
if (typeof ReadableStream !== "undefined") {
// MS Edge may say it has ReadableStream but they are not up to spec yet.
try {
// eslint-disable-next-line no-new
new ReadableStream({
start(controller) {
controller.close();
},
});
isReadableStreamSupported = true;
} catch (e) {
// The ReadableStream constructor cannot be used.
}
if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("CHROME")) {
// Slightly reduce the size of the Chromium-extension, given
// that `ReadableStream` has been supported since Chrome 43.
return;
}
if (isReadableStreamSupported) {
if (globalThis.ReadableStream || !isNodeJS) {
return;
}
globalThis.ReadableStream =