date.getFullYear is not a function

function formatNumber(n) {

  n = n.toString()

  return n[1] ? n : ‘0’ + n

}

function formatTime(date) {

  var year = date.getFullYear()

  var month = date.getMonth() + 1

  var day = date.getDate()

  var hour = date.getHours()

  var minute = date.getMinutes()

  var second = date.getSeconds()

  return [year, month, day].map(formatNumber).join(‘/’) + ’ ’ + [hour, minute, second].map(formatNumber).join(‘:’)

}

打印处理提示date.getFullYear is not a function