<script>
  //myTime typeof //object
  window.onload = function() {
    var obody = document.body;
    //设置一个定时器，每过一秒钟，自动加一秒
    setInterval(fnTime, 1000)
    //如果不执行这个函数，第一次打开时，会过一秒钟才出来
    fnTime();
    function fnTime() {
      var myTime = new Date();
      var iYear = myTime.getFullYear();
      var iMonth = myTime.getMonth() + 1;
      var iDate = myTime.getDate();
      var iWeek = myTime.getDay();
      var iHours = myTime.getHours();
      var iMinutes = myTime.getMinutes();
      var iSeconds = myTime.getSeconds();
      var str = "";
      if(iWeek === 0) iWeek = "星期日"
      if(iWeek === 1) iWeek = "星期一"
      if(iWeek === 2) iWeek = "星期二"
      if(iWeek === 3) iWeek = "星期三"
      if(iWeek === 4) iWeek = "星期四"
      if(iWeek === 5) iWeek = "星期五"
      if(iWeek === 6) iWeek = "星期六"
      str = iYear + "年" + iMonth + "月" + iDate + "日 " + iWeek + " " + toTwo(iHours) + "时" + toTwo(iMinutes) + "分" + toTwo(iSeconds) + "秒"
      obody.innerHTML = str;
    }
    console.log(toTwo(05))//05
    console.log(toTwo(15))//15
    //这个函数主要是让:时分秒到59秒时，再走一秒就变成了0，而不是00，所以要转换一下
    function toTwo(n) {
      /*
       if(n < 10) {
       return "0" + n;
       } else {
       return "" + n;
       }
       */
      //我们可以用三目
      return n < 10 "0" + n : "" + n
    }
  }
</script>