Youtube Quality.js

// ==UserScript==
// @name         Youtube quality
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        https://www.youtube.com/*
// @run-at       document-end
// @grant        none
// ==/UserScript==

(async function() {

    console.log("I am here :D ")

    await waitTillElementAppear("ytp-button ytp-settings-button",0)
    click("ytp-button ytp-settings-button", 0)

    sleep(100)
    await waitTillElementAppear("ytp-menuitem", 3)
    click("ytp-menuitem", 4)

    //await waitTillElementAppear("ytp-menuitem-label", 4)
    //click("ytp-menuitem-label", 4)

    console.log("I am here :P ")

    //ytp-popup ytp-settings-menu
    //ytp-menuitem
})();

async function waitTillElementAppear(className, elementIndex) {
    var wasExceptionThrown;
    do{
        console.log("1234" + className)
       wasExceptionThrown = false;
        try{
          var hasPopupAppeared = document.getElementsByClassName(className)[elementIndex].innerText != null
        } catch(e){
            wasExceptionThrown = true
            await sleep(100)
        }
    } while(wasExceptionThrown || !hasPopupAppeared);
}


function click(className, elementIndex) {
    var evt = document.createEvent("MouseEvents");
    evt.initMouseEvent("click", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
    document.getElementsByClassName(className)[elementIndex].dispatchEvent(evt);
}


function sleep(ms) {
       return new Promise(resolve => setTimeout(resolve, ms));
}