// ==UserScript==
// @name        Play Single Video Only
// @namespace   UserScript
// @match       https://www.youtube.com/*
// @match       https://www.facebook.com/*
// @version     1.2
// @license     MIT
// @author      CY Fung
// @description Pause your background video when you play another video in another tab.
// @run-at      document-start
// @grant       GM_addValueChangeListener
// @grant       GM.setValue
// ==/UserScript==
(() => {
const ways = {
'www.youtube.com': {
findVideo: () => {
return document.querySelector('#movie_player video');
},
testVideo: (video) => {
if (video.volume > 1e-5 && video.muted === false) {
} else {
return false;
}
if (HTMLElement.prototype.matches.call(video, '#movie_player video')) return true;
}
},
'www.facebook.com': {
findVideo: () => {
return [...document.querySelectorAll('#watch_feed video')].filter(elm => elm.paused === false)[0]
},
testVideo: (video) => {
if (video.volume > 1e-5 && video.muted === false) {
} else {
return false;
}
if (HTMLElement.prototype.matches.call(video, '#watch_feed video')) return true;
}
}
};
const { findVideo, testVideo } = ways[location.hostname];
if (typeof findVideo !== 'function' || typeof testVideo !== 'function') return;
GM_addValueChangeListener("t9opC", function (key, oldValue, newValue, remote) {
if (remote) {
let video = findVideo();
if (video && video.paused === false && video.volume > 1e-5 && video.muted === false && testVideo(video)) {
HTMLVideoElement.prototype.pause.call(video);
}
}
});
document.addEventListener('play', function (evt) {
if (!evt || !evt.isTrusted) return;
const target = (evt || 0).target;
if (target instanceof HTMLVideoElement) {
if (testVideo(target)) {
GM.setValue('t9opC', Date.now());
}
}
}, true);
})();