获取当前日期的起始周时间

/*
	获取当前周的起始时间
*/
exports.weekStart = function (){
	var date = new Date
	var week = date.getDay()
	var h = date.getHours()
	var m = date.getMinutes()
	var S = date.getSeconds()
	var s = date.getMilliseconds()
	var day
	switch(week){
		case 0: day = 6
		break
		case 1: day = 0
		break
		default: day = week - 1
	}
	return new Date(Date.now()- 3600*24*1000*day - (h*3600*1000) - (m *60*1000) - (S*1000) - s)
}