video标签Show里this.setData修改video组件的initial-time不生效？

var newdate = newDate().getTime()

var olddata = that.data.startButtonTime

var olddatas = olddata.replace(/-/g, ‘/’);

var olddate = newDate(olddatas).getTime()

var time = (newdate - olddate) / 1000

that.setData({

duration: time

})