/**

* 获取本周、本季度、本月、上月的开始日期、结束日期

*/

var now = new Date(); //当前日期 

var nowDayOfWeek = now.getDay(); //今天本周的第几天 

var nowDay = now.getDate(); //当前日 

var nowMonth = now.getMonth(); //当前月 

var nowYear = now.getYear(); //当前年 

nowYear += (nowYear < 2000) ? 1900 : 0; //

var lastMonthDate = new Date(); //上月日期

lastMonthDate.setDate(1);

lastMonthDate.setMonth(lastMonthDate.getMonth()-1);

var lastYear = lastMonthDate.getYear();

var lastMonth = lastMonthDate.getMonth();

//格式化日期：yyyy-MM-dd 

function formatDate(date) { 

var myyear = date.getFullYear(); 

var mymonth = date.getMonth()+1; 

var myweekday = date.getDate(); 

if(mymonth < 10){ 

mymonth = "0" + mymonth; 

} 

if(myweekday < 10){ 

myweekday = "0" + myweekday; 

} 

return (myyear+"-"+mymonth + "-" + myweekday); 

} 

//获得某月的天数 

function getMonthDays(myMonth){ 

var monthStartDate = new Date(nowYear, myMonth, 1); 

var monthEndDate = new Date(nowYear, myMonth + 1, 1); 

var days = (monthEndDate - monthStartDate)/(1000 * 60 * 60 * 24); 

return days; 

} 

//获得本季度的开始月份 

function getQuarterStartMonth(){ 

var quarterStartMonth = 0; 

if(nowMonth<3){ 

quarterStartMonth = 0; 

} 

if(2<nowMonth && nowMonth<6){ 

quarterStartMonth = 3; 

} 

if(5<nowMonth && nowMonth<9){ 

quarterStartMonth = 6; 

} 

if(nowMonth>8){ 

quarterStartMonth = 9; 

} 

return quarterStartMonth; 

} 

//获得本周的开始日期 

function getWeekStartDate() { 

var weekStartDate = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek); 

return formatDate(weekStartDate); 

} 

//获得本周的结束日期 

function getWeekEndDate() { 

var weekEndDate = new Date(nowYear, nowMonth, nowDay + (6 - nowDayOfWeek)); 

return formatDate(weekEndDate); 

} 

//获得本月的开始日期 

function getMonthStartDate(){ 

var monthStartDate = new Date(nowYear, nowMonth, 1); 

return formatDate(monthStartDate); 

} 

//获得本月的结束日期 

function getMonthEndDate(){ 

 var days= getMonthDays(nowMonth);//获取当月总共有多少天

 var monthEndDate = new Date(nowYear, nowMonth, days); 

 return formatDate(monthEndDate); //返回当月结束时间

}

注意：因为上面这个方法里的getMonthDays(nowMonth)方法 我尝试使用失败，我不知道是什么原因 所以我用了另外个方法如下（获得某月的天数,需要配合文章开头的公式 ）：

//获得某月的天数 （与上面有重复可删除，不然本月结束日期报错）

    function getMonthDays(nowyear,myMonth){

     var lastMonthStartDate = new Date(nowyear, lastMonth, 1);

     var lastMonthEndDate= new Date(nowyear, lastMonth+ 1, 1);

     var days = (lastMonthEndDate- lastMonthStartDate) / (1000 * 60 * 60 * 24);//格式转换

    alert(days);

   }

//获得上月开始时间

function getLastMonthStartDate(){

var lastMonthStartDate = new Date(nowYear, lastMonth, 1);

return formatDate(lastMonthStartDate); 

}

//获得上月结束时间

function getLastMonthEndDate(){

var lastMonthEndDate = new Date(nowYear, lastMonth, getMonthDays(lastMonth));

return formatDate(lastMonthEndDate); 

}

//获得本季度的开始日期 

function getQuarterStartDate(){ 

var quarterStartDate = new Date(nowYear, getQuarterStartMonth(), 1); 

return formatDate(quarterStartDate); 

} 

//或的本季度的结束日期 

function getQuarterEndDate(){ 

var quarterEndMonth = getQuarterStartMonth() + 2; 

var quarterStartDate = new Date(nowYear, quarterEndMonth, getMonthDays(quarterEndMonth)); 

return formatDate(quarterStartDate); 

}

//获取本年开始-当前时间

var currentYear=now.getFullYear();//获得当前年份4位年

var currentYearFirstDate=new Date(currentYear,0,1); //本年第一天

var startTime = currentYearFirstDate.getFullYear() + '-' + (currentYearFirstDate.getMonth() +1) + '-' + currentYearFirstDate.getDate()+''+currentYearFirstDate.getHours()+':'+currentYearFirstDate.getMinutes()+':'+

currentYearFirstDate.getSeconds(); //格式化本年第一天日期

var currentYearEndDate=now; //当前时间