getYMDHMS (timestamp) {
      let time = new Date(timestamp)
      let year = time.getFullYear()
      let month = time.getMonth() + 1
      let date = time.getDate()
      let hours = time.getHours()
      let minute = time.getMinutes()
      let second = time.getSeconds()

      if (month < 10) { month = '0' + month }
      if (date < 10) { date = '0' + date }
      if (hours < 10) { hours = '0' + hours }
      if (minute < 10) { minute = '0' + minute }
      if (second < 10) { second = '0' + second }
      return year + '-' + month + '-' + date + ' ' + hours + ':' + minute + ':' + second
}

 // 使用es6的padStart()方法来补0
  getYMDHMS (timestamp) {
      let time = new Date(timestamp)
      let year = time.getFullYear()
      const month = (time.getMonth() + 1).toString().padStart(2, '0')
      const date = (time.getDate()).toString().padStart(2, '0')
      const hours = (time.getHours()).toString().padStart(2, '0')
      const minute = (time.getMinutes()).toString().padStart(2, '0')
      const second = (time.getSeconds()).toString().padStart(2, '0')

      return year + '-' + month + '-' + date + ' ' + hours + ':' + minute + ':' + second
}