如上视频，改变current时不是正确的过渡效果

如下代码，点击事件

// 上一题
prevQuestion: function () {
    if (this.data.current === 0) return;
    let i = this.data.current - 1;
    console.log('i', i);
    this.setData({
      current: i,
      progressWidth: ((i+1) / this.data.examList.length) * 100
    });
},
// 下一题
nextQuestion: function () {
    if ((this.data.current+1) >= this.data.examList.length) return;
    let i = this.data.current + 1;
    console.log('i', i);
    this.setData({
      current: i,
      progressWidth: ((i+1) / this.data.examList.length) * 100
    });
}

怎样可以有正确的过渡效果