JS获取本周、本季度、本月、上月的开始日期、结束日期详解编程语言

/** 
* 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);     
}     
//今天 
var getCurrentDate = new Date(nowYear, nowMonth, nowDay); 
var getCurrentDate  = formatDate(getCurrentDate) 
//昨天 
var getYesterdayDate = new Date(nowYear, nowMonth, nowDay - 1); 
var getYesterdayDate =  formatDate(getYesterdayDate);   
//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 monthEndDate = new Date(nowYear, nowMonth, getMonthDays(nowMonth));     
return formatDate(monthEndDate);    
}    
//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);    
}