YouTube replaced Promise with polyfill in some old browsers.
// ==UserScript==
// @name Native Promise for YouTube
// @namespace http://tampermonkey.net/
// @version 0.1.4
// @license MIT
// @description YouTube replaced Promise with polyfill in some old browsers.
// @author CY Fung
// @match https://*.youtube.com/*
// @match https://www.youtube-nocookie.com/embed/*
// @run-at document-start
// @grant none
// @unwrap
// @allFrames
// @inject-into page
// @compatible firefox Firefox >= 52 && Firefox < 69
// @compatible edge Edge >= 15 && Edge < 79
// ==/UserScript==
(function () {
'use strict';
if (typeof PromiseRejectionEvent !== 'function') {
/*
Minimum Requirement:
async ()=>{}: Chrome 55, Edge 15, Safari 11, Firefox 52, Opera 42
Target Browsers below the following versions:
PromiseRejectionEvent: Chrome 49, Edge 79, Safari 11, Firefox 69, Opera 36
This script will only work for
Edge >= 15 && Edge < 79
Firefox >= 52 && Firefox <= 69
*/
try {
const truePromise = (async () => { })().constructor; // suppress polyfill if the old browser can support async arrow function;
window.PromiseRejectionEvent = (() => {
throw 'PromiseRejectionEvent is not supported';
}); // Waterfox Classic does not have "PromiseRejectionEvent"
if (truePromise !== Promise) window.Promise = truePromise; // if the script runs after polyfill.
} catch (e) {
throw 'Your browser is too old. This script will not work for you';
}
}
})();