// ==UserScript==
// @name        YouTube Wait for Me - Pause and Start Player in Background Tabs
// @author      Jefferson "jscher2000" Scher
// @namespace   JeffersonScher
// @version     0.7
// @copyright   Copyright 2016 Jefferson Scher
// @license     BSD 3-clause
// @description Pause the video in YouTube tabs opened in the background, play on activation 2016-08-18 (I know, it doesn't pause fast enough)
// @include     http*://www.youtube.com/*
// @grant       none
// ==/UserScript==
// See: https://developer.mozilla.org/docs/Web/API/Page_Visibility_API
var videoElement = document.querySelector('#movie_player video');
if (videoElement){
if (document["hidden"]) { // background tab
// Mute the player ASAP
videoElement.muted = true;
// Pause the player
videoElement.pause();
// Seek to the beginning
videoElement.currentTime = 0;
// Set up event handler to watch for tab becoming visible
document.addEventListener("visibilitychange", handleVisibilityChange, false);
}
}
function handleVisibilityChange() {
if (document["hidden"]) {
// Pause the player
videoElement.pause();
} else {
// R###me the video after a quarter second
window.setTimeout(function(){videoElement.play()}, 250);
videoElement.muted = false;
// We're not going to pause again, so remove event listener
document.removeEventListener("visibilitychange", handleVisibilityChange, false);
}
}