设置一个箭头函数

    1. let timer = (){
    2. }

    在箭头函数内设置

    • 获取当前时间 new Date()
    • 设置你想要的时间 new Date('2020-12-5 9:00:00')
    • 获取相差时间的毫秒 x = 你的时间.getTime() - new Date().getTime()

    • 设置小时，分钟，秒

      1.     let hours = Math.floor(OverTime / 1000 / 60 / 60 ); // 获取小时
      2.     let minutes = Math.floor(OverTime / 1000 / 60 % 60); //获取分钟数
      3.     let seconds = Math.floor(OverTime / 1000 % 60); //获取秒数

    • 判断返回的数据如果是10以内的数，则加个0

      1.     hours < 10 ? hours = "0" + hours : hours;
      2.     minutes < 10 ? minutes = "0" + minutes : minutes;
      3.     seconds < 10 ? seconds = "0" + seconds : seconds;

    • 整合数据

      1. let rels = `${hours}:${minutes}:${seconds}`

    • 显示

      1.   let timer = () => {
      2.     let time = new Date()
      3.     let nowTime = new Date('2020-12-5 9:00:00')     
      4.     let OverTime = nowTime.getTime() - time.getTime()
      5.     let hours = Math.floor(OverTime / 1000 / 60 / 60 ); // 获取小时
      6.     let minutes = Math.floor(OverTime / 1000 / 60 % 60); //获取分钟数
      7.     let seconds = Math.floor(OverTime / 1000 % 60); //获取秒数
      8.     hours < 10 ? hours = "0" + hours : hours;
      9.     minutes < 10 ? minutes = "0" + minutes : minutes;
      10.     seconds < 10 ? seconds = "0" + seconds : seconds;
      12.     let rels = `${hours}:${minutes}:${seconds}`
      13.     this.setData({time : rels })
      14.   }
      16.   setInterval(()=>{
      17.     timer()
      18.   },1000)

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