jquery 时间封装包

$(function () {            var _timeHelper = new TimeHelper();            _timeHelper.MonthStartDateByNum(-1);            _timeHelper.MonthEndDate();            _timeHelper.WeekStartDateByNum(2);            _timeHelper.WeekStartDate();            _timeHelper.WeekEndDate();            _timeHelper.MonthStartDate();        })        function TimeHelper() {        }        TimeHelper.prototype.WeekStartDate = function () {            var now = new Date();            var start = new Date();            var n = now.getDay();            if (n == 0) { n = 7; }            start.setDate(now.getDate() - n + 1);            var _date = new Date(start.getFullYear(), start.getMonth(), start.getDate());            return _date;        }        TimeHelper.prototype.WeekStartDateByNum = function (week_num) {            var now = new Date();            var _temp = new Date();            now.setDate(_temp.getDate() + 7 * week_num);            var n = now.getDay();            if (n == 0) { n = 7; }            var start = new Date(now.getFullYear(),now.getMonth(),now.getDate());            start.setDate(now.getDate() - n + 1);            var _date = new Date(start.getFullYear(), start.getMonth(), start.getDate());            return _date;        }        TimeHelper.prototype.WeekEndDate = function () {            var week_start = this.WeekStartDate();            var week_end = new Date();            week_end.setDate(week_start.getDate() + 6);             var _date = new Date(week_end.getFullYear(), week_end.getMonth(), week_end.getDate());            return _date;        }        TimeHelper.prototype.MonthStartDate = function () {            var now = new Date();            var _date = new Date(now.getFullYear(), now.getMonth(), 1);            return _date;        }        TimeHelper.prototype.MonthStartDateByNum = function (month_num) {            var now = new Date();            var _date = new Date(now.getFullYear(), now.getMonth() + month_num, 1);            return _date;        }        TimeHelper.prototype.MonthEndDate = function () {            var now = new Date();            var nextMonth = new Date(now.getFullYear(), now.getMonth() + 1, 1);            nextMonth.setDate(nextMonth.getDate() - 1);            var _date = new Date(nextMonth.getFullYear(), nextMonth.getMonth(), nextMonth.getDate());            return _date;        }