function NewDate(str)

     {

         str=str.split('-');

         var date=new Date();

         date.setUTCFullYear(str[0], str[1]-1, str[2]);

         date.setUTCHours(0, 0, 0, 0);

         return date;

     }

//格式化日期格式    stime=stime.format("yyyyMMdd");

Date.prototype.format = function (format) {

	var o = {

		"M+": this.getMonth() + 1, //month

		"d+": this.getDate(), //day

		"h+": this.getHours(), //hour

		"m+": this.getMinutes(), //minute

		"s+": this.getSeconds(), //second

		"q+": Math.floor((this.getMonth() + 3) / 3), //quarter

		"S": this.getMilliseconds() //millisecond

	}

	if (/(y+)/.test(format)) format = format.replace(RegExp.$1,

	(this.getFullYear() + "").substr(4 - RegExp.$1.length));

	for (var k in o) if (new RegExp("(" + k + ")").test(format))

		format = format.replace(RegExp.$1,

		RegExp.$1.length == 1 ? o[k] :

		("00" + o[k]).substr(("" + o[k]).length));

	return format;

}

var curDateTime = new Date();

var nowYear = curDateTime.getFullYear();

var nowMonth = curDateTime.getMonth();

var nowDay = curDateTime.getDate();

var nowDayOfWeek = curDateTime.getDay();

console.log('year:'+nowYear+',month:'+nowMonth+',day:'+nowDay+',dayofweek:'+nowDayOfWeek);

var start=new Date(),end=new Date();

//1昨天

//curDateTime.setDate(curDateTime.getDate()-1);

//start=curDateTime.format("yyyyMMdd");

//end=curDateTime.format("yyyyMMdd");

//console.log("昨天:"+start+"  "+end);

//2前天

//curDateTime.setDate(curDateTime.getDate()-2);

//start=curDateTime.format("yyyyMMdd");

//end=curDateTime.format("yyyyMMdd");

//console.log("前天:"+start+"  "+end);

//本周

//start=new Date(nowYear,nowMonth,(nowDay-nowDayOfWeek+1));

//start=start.format("yyyyMMdd");

//end==new Date(nowYear,nowMonth,curDateTime.getDate());

//end=end.format("yyyyMMdd");

//console.log("本周:"+start+"  "+end);

//上周

//start=new Date(nowYear,nowMonth,(nowDay-nowDayOfWeek-6));

//start=start.format("yyyyMMdd");

//curDateTime.setDate(nowDay-nowDayOfWeek);

//end=curDateTime.format("yyyyMMdd");

//console.log("上周:"+start+"  "+end);

//本月

//start=curDateTime.format("yyyyMM01");

//本月的截至日期只统计到当前

//end=curDateTime.format("yyyyMMdd");

//console.log("本月:"+start+"  "+end);

//上月

start =new Date(nowYear,nowMonth-1,1);

start=start.format("yyyyMMdd");

end=new Date(nowYear,nowMonth,1);

end.setDate(end.getDate()-1);

end=end.format("yyyyMMdd");

console.log("上月:"+start+"  "+end);