效果图

子组件

新建一个timer.vue文件

<template>
  <span :class="{red: string >= 600}">{{ string | formatDurationS }}</span>
</template>
<script>

export default {
  name: 'timer',
  props: {
    startTimer: {
      type: [String, Number],
      default: 0
    },
    currentTimer: {
      type: [String, Number],
      default: 0
    }
  },
  data() {
    return {
      string: '--:--:--', // '00:00:00',
      step: 0,
      intervalName: ''
    }
  },
  watch: {
    currentTimer: {
      handler: function(nev, oldv) {
        if (this.intervalName) {
          clearInterval(this.intervalName)
        }
        this.step = this.startTimer
        let _str = Math.round((this.currentTimer - this.startTimer) / 1000)
        this.string = _str < 0 ? 0 : _str
        this.intervalName = setInterval(() => {
          this.string++
        }, 1000)
      },
      immediate: true
    }
  },
  beforeDestroy() {
    clearInterval(this.intervalName)
    this.intervalName = null
  }
}

</script>
<style scoped lang="less">
.red {
  color: #F03E3E;
}
</style>

父组件

导入子组件并注册

<TIMER ref="timerFun" :currentTimer="timeStamp" :startTimer="item.actionTime"></TIMER>


import TIMER from '@/components/timer.vue'

timeStamp: Date.now(),

components: {
  TIMER
}

• startTimer： 开始计时的时间戳
• currentTimer: 当前本地时间时间戳
• 两者的差值就是起始的持续时间