Twitch doubleclick

// ==UserScript==
// @name         Twitch doubleclick
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Add doubleclick listener to switch to full screen
// @author       Ravana
// @match        https://www.twitch.tv/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    var init = function(){
        console.log("init attempt");
        document.getElementsByClassName("player-video")[0].addEventListener("dblclick", function(){
            document.getElementsByClassName("qa-fullscreen-button")[0].click();
        });

        clearInterval(interval);
        console.log("init success");
    };

    var interval = setInterval(init, 1000);
})();