1     format(interval) {
   //格式化时间 2         interval = interval | 0//interval为毫秒数 3         const minute = interval / 60 | 0//分钟数为总时间/60 4         const second = this._pad(interval % 60) 5         return `${minute}:${second}` 6       }, 7       _pad(num, n = 2) {
   //格式化时间，给秒数补0； 8         let len = num.toString().length 9         while (len < n) {10           num = '0' + num11           len++12         }13         return num14       },