JavaScript 前端date（时间）工具类

1、格式化时间

/**
	 * 格式化时间
	 *
	 * @param {time} 时间
	 * @param {cFormat} 格式
	 * @return {String} 字符串
	 * @example formatTime('2018-1-29', '{y}/{m}/{d} {h}:{i}:{s}:{a}') // -> 2018/01/29 00:00:00:五
	*/
  formatTime = (time, cFormat) => {
	 	if(arguments.length === 0) return null
		if((time + '').length === 10) {
			time = +time * 1000
		}

		var format = cFormat || '{y}-{m}-{d} {h}:{i}:{s}', date
		if(typeof time === 'object') {
			date = time
		} else {
			date = new Date(time)
		}

		var formatObj = {
			y: date.getFullYear(),
			m: date.getMonth() + 1,
			d: date.getDate(),
			h: date.getHours(),
			i: date.getMinutes(),
			s: date.getSeconds(),
			a: date.getDay()
		}

		var time_str = format.replace(/{(y|m|d|h|i|s|a)+}/g, (result, key) => {
			var value = formatObj[key]
			if (key === 'a') return ['一', '二', '三', '四', '五', '六', '日'][value - 1]
				if (result.length > 0 && value < 10) {
					value = '0' + value
				}
				return value || 0
			})

		return time_str
	},

2、转换秒数

	/**
		 * 转换秒数
		 * @param    {s} 秒数
		 * @return   {string} 字符串
		 *
		 * @example formatHMS(3610) // -> 1h0m10s
		*/
		formatHMS = s => {
		  var str = ''
		 	if(s > 3600) {
		 		str = Math.floor(s/3600) + 'h' + Math.floor(s%3600/60) + 'm' + s%60 + 's'
		 	} else if(s > 60) {
		 		str = Math.floor(s/60) + 'm' + s%60 + 's'
		 	} else {
		 		str = s%60 + 's'
		 	}
		 	return str
		},

3、获得某月有多少天

/**
		 * 获得某月有多少天
		 * @param    {time} 日期
		 * @return   {string} 字符串
		 *
		 * @example getMonthOfDay('2018-2-22') // -> 29  
		*/
		getMonthOfDay = time => {
		  var date = new Date(time),
		 	year = date.getFullYear(),
		 	mouth = date.getMonth() + 1,
		 	days;
			if(mouth == 2) { //当月份为二月时，根据闰年还是非闰年判断天数
				days = (year%4==0 && year%100==0 && year%400==0) || (year%4==0 && year%100!=0) ? 28 : 29
			} else if(mouth == 1 || mouth == 3 || mouth == 5 || mouth == 7 || mouth == 8 || mouth == 10 || mouth == 12) {
				//月份为：1,3,5,7,8,10,12 时，为大月.则天数为31；
				days = 31
			} else {
				days = 30
			}
			return days
		},

4、获取某年的第一天

/*获取某年的第一天*/
  getFirstDayOfYear = (time) => {
	  var year = new Date(time).getFullYear()
	  return year + '-01-01 00:00:00'
  },

5、获取某年的最后一天

 /*获取某年的最后一天*/
  getLastDayOfYear = (time) => {
	  var year = new Date(time).getFullYear(),
	  dateString = year + '-12-01 00:00:00',
	  endDay = getMonthOfDay(dateString)
	  return year + '-12-' + endDay + ' 23:59:59'
  },

6、获取某年有多少天

 /*获取某年有多少天*/
  getYearOfDay = time => {
	  var firstDayYear = getFirstDayOfYear(time),
			lastDayYear = getLastDayOfYear(time),
			numSecond = (new Date(lastDayYear).getTime() - new Date(firstDayYear).getTime())/1000;
	  return Math.ceil(numSecond/(24*3600))
  },

7、获取某个日期是当年中的第几天

 /*获取某个日期是当年中的第几天*/
  getDayOfYear = time => {
    var firstDayYear = getFirstDayOfYear(time),
  		numSecond = (new Date(time).getTime() - new Date(firstDayYear).getTime())/1000;
    return Math.ceil(numSecond/(24*3600))
  },

8、 获取某个星期在这一年的第几周

	/*获取某个星期在这一年的第几周*/
	  getDayOfYearWeek = time => {
		  var numdays = getDayOfYear(time)
		  return Math.ceil(numdays/7)
	  }