Bookmarklet to disable visibility change events (to keep websites playing content even when out of focus) (based on https://greasyfork.org/en/scripts/429635-always-on-focus/code )

visChangeBlocker.js

javascript:(function(){window.onblur=null;window.blurred=false;Object.defineProperty(document,"hasFocus",{get:function(){return true}});Object.defineProperty(document,"webkitHidden",{get:function(){return false}});["hidden","mozHidden","msHidden","webkitHidden"].forEach(function(t){Object.defineProperty(document,t,{value:false,configurable:true})});["visibilitychange","webkitvisibilitychange","mozvisibilitychange","msvisibilitychange"].forEach(function(t){document.removeEventListener(t,document["on"+t])});var e=function(t){["blur","mouseleave","mouseout"].includes(t.type)&&(t.target instanceof HTMLInputElement||t.target instanceof HTMLAnchorElement||t.target instanceof HTMLSpanElement)&&t.preventDefault(),t.stopPropagation(),t.stopImmediatePropagation()};["blur","mouseleave","mouseout"].forEach(function(t){window.addEventListener(t,e,true),document.addEventListener(t,e,true)})})();