<script>
// 未来的终止时间 2018.10.10 23:59:59
const futureDate = new Date(2018, 10, 10, 23, 59, 59)

export default {
  data () {
    return {
      time: {
        day: '69', // String
        hour: '59', // String
        minute: '59', // String
        seconds: '59' // String
      }
    }
  },
  mounted () {
    this.countDownComputer() // 初始化倒计时
    this.countDownMachine() // 开始倒计时
  },
  methods: {
    addZero: num => num.toString().length === 1 ? `0${num}` : num,
    formateCountDown () {
      const time = this.time
      return `${time.day} 天 ${time.hour} 时 ${time.minute} 分 ${time.seconds} 秒`
    },
    // 倒计时计算器
    countDownComputer () {
      let nowTime = Date.now()
      const secondMinuend = 1000
      const minMinuend = 1000 * 60
      const hourMinuend = 1000 * 60 * 60
      const dayMinuend = 1000 * 60 * 60 * 24
      let countDownSeconds = futureDate - nowTime
      const day = (countDownSeconds / dayMinuend).toFixed()
      const hour = (countDownSeconds % dayMinuend / hourMinuend).toFixed()
      const minute = (countDownSeconds % dayMinuend % hourMinuend / minMinuend).toFixed()
      const seconds = (countDownSeconds % dayMinuend % hourMinuend % minMinuend / secondMinuend).toFixed()
      if (day !== this.time.day) this.time.day = this.addZero(day)
      if (hour !== this.time.hour) this.time.hour = this.addZero(hour)
      if (minute !== this.time.minute) this.time.minute = this.addZero(minute)
      if (seconds !== this.time.seconds) this.time.seconds = this.addZero(seconds)
    },
    // 倒计时启动器
    countDownMachine () {
      const vm = this
      const perMinute = 1000
      setInterval(() => vm.countDownComputer(), perMinute)
    }
  }
}
</script>