核心程式碼：

  onMusicTap:function(event){
    var isPlayingMusic = this.data.isPlayingMusic;
    if(isPlayingMusic){
      wx.pauseBackgroundAudio();
    // 要隨時更新isPlayingMusic的值
      this.setData({
       isPlayingMusic:false 
       })
    }
    else{
      wx.playBackgroundAudio({
        dataUrl: 'http://118.112.10.149/amobile.music.tc.qq.com/C400003OUlho2HcRHC.m4a?guid=2044940640&vkey=9423687E043FB255EDB406724608FB7C745E15838B5A3CC4352F0BD2249C870766F27A9559DA38FBE7941C1096CEA5D2D85F9E2BE5A71EB5&uin=0&fromtag=66',
        title:'告白氣球-周杰倫'
      })
    }
        // 要隨時更新isPlayingMusic的值
      this.setData({
       isPlayingMusic:true
       }) 
  }