watchMusicState(){
        let _this = this;
        let $audio = document.getElementsByTagName('audio')[0];//获取音乐DOM节点
        let playOrPause = document.getElementsByClassName('playOrPause')[0];
        // console.log($audio);
        $audio.addEventListener("playing", function(){        //播放状态Doing

            _this.playState = true;//播放状态
                console.log('开')
        });
        $audio.addEventListener("pause", function(){ //暂停状态Doing

            
            _this.playState = false;//暂停状态
                console.log('关')

        });
    }