code: function isLeapYear (date) {
    var year
    var currentDate = date ? XEUtils.toStringDate(date) : new Date()
    if (isDate(currentDate)) {
      year = currentDate.getFullYear()
      return (year % 4 === 0) && (year % 100 !== 0 || year % 400 === 0)
    }
    return false
  }
docs: 判断是否闰年
  
  @param {Date} date 日期或数字
  @return {Boolean}