js判断时间格式不能超过30天

    let first = this.data.date  //开始时间
    let second = e.detail.value  //结束时间
    var data1 = Date.parse(first.replace(/-/g, "/"));
    var data2 = Date.parse(second.replace(/-/g, "/"));
    var datadiff = data2 - data1;
    var time = 31 * 24 * 60 * 60 * 1000;
    console.log(first.length)
    console.log(second.length)
    if (first.length > 0 && second.length > 0) {
      if (datadiff < 0 || datadiff > time) {
        wx.showToast({
          title: '前后时间间隔不能大于31天',
        icon: 'none',
        duration: 2000,
      })
      this.setData({
        date1: "结束时间"
      })
        return false;
      }
    }