取最大值

  1.         var arr = [4,5,6];
  2.        /*  Math.max
  3.         var max = arr[0];
  4.         for(var i=1;i<arr.length;i++){
  5.             if(arr[i]>max){
  6.                 max = arr[i];
  7.             }
  8.         } */
  9.         console.log(max)
  10.         console.log(Math.max(...arr))
  11.         console.log(Math.min(...arr))

处理数组

  1.         function handleNum(num){
  2.             if(num>=100000000){
  3.                 num = num/100000000+"亿"
  4.             }else if(num>=10000){
  5.                 num = num/10000+"万"
  6.             }
  7.             return num+"";
  8.         }
  9.         var arr = [
  10.             /* 4000 */
  11.             {name:"你好",playCount:4000},
  12.             /* 40万 */
  13.             {name:"它",playCount:400040},
  14.             /* 2亿 */
  15.             {name:"谁",playCount:200000000}
  16.         ]
  17.         arr.forEach(item=>{
  18.             item.playCount = handleNum(item.playCount);
  19.         })
  20.         console.log(arr)

image.png

时间戳

  1.         var time = "2021-10-13 17:10:10"
  2.         /* 多个小时,多分钟,多少秒 */;
  3.         /* 1、获取当前时间的毫秒数 */
  4.         var d = new Date();
  5.         // console.log(d.getTime())
  6.         var startTime = d.getTime();
  7.         /* 2、获取活动开始时间的毫秒 */
  8.         var endTime = new Date(time).getTime();
  9.         // console.log(endTime)
  10.         /* 3、得到中间间隔的毫秒数 */
  11.         var gapTime = endTime -startTime;
  13.         var seconds = Math.floor(gapTime/1000)
  14.         console.log(seconds)
  15.         var hours = Math.floor(seconds/3600);
  16.         console.log(hours)
  17.         seconds = seconds - 3600*hours;
  18.         var minutes = Math.floor(seconds/60);
  19.         console.log(minutes)
  20.         seconds = seconds - minutes*60;
  21.         console.log(seconds)
  22.         /* var time = "2021-10-13 21:30:00"  第一个需求*/
  23.         /*  var  time ="2021-10-19 08:30:00" 还有几天几小时几分 */