監聽Audio的播放狀態

監聽音樂播放狀態：改變播放或暫停按鈕
    watchMusicState(){
        let _this = this;
        let $audio = document.getElementsByTagName('audio')[0];//獲取音樂DOM節點
        let playOrPause = document.getElementsByClassName('playOrPause')[0];
        // console.log($audio);
        $audio.addEventListener("playing", function(){        //播放狀態Doing
                playOrPause.src = require('../assets/img/pause.svg')//背景音樂是播放還是暫停
                _this.playState = true;//播放狀態
        });$audio.addEventListener("pause", function(){ //暫停狀態Doing
                playOrPause.src = require('../assets/img/play.svg')//背景音樂是播放還是暫停
                _this.playState = false;//暫停狀態

        });
    },