事件监听之后，暂停不了

Question

window.onload = function(){ var music = document.getElementById("music");    var audio = document.getElementsByTagName("audio")[0];            audio.addEventListener("ended",function(event){      music.setAttribute("class","");      },false);                music.addEventListener("touchstart",function(event) { if (audio.paused) { audio.play(); this.setAttribute("class","play"); }else{ audio.pause(); this.setAttribute("class",""); }; },false);};