js 获取 本周、上周、本月、上月、本季度、上季度的开始结束日期

/**
 * 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);
}
//获得上周的开始日期
function getLastWeekStartDate() {
  var weekStartDate = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek - 7);
  return formatDate(weekStartDate);
}
//获得上周的结束日期
function getLastWeekEndDate() {
  var weekEndDate = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek - 1);
  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);
}

　　

js 计算月/周的第一天和最后一天

因为项目开发中遇到需要向后台传本周的开始和结束时间，以及上一周的起止时间，就琢磨了半天，总算写出来一套，写篇文章是为了方便自己记忆，也是分享给需要的人，水平有限，写的不好请见谅：

getDateStr3函数是为了把时间对象转变为yy-mm-dd的字符串，方便传值；

getWeekStartAndEnd函数是获取周的起止时间，并且用getDateStr3转换成字符串放到数组中，其中参数0代表当前周，-1代表前一周，-2代表上上周，以此类推，反过来也可以1代表下一周；

getMonthStartAndEnd函数是获取月的起止时间，传参同上

//获取当前日期yy-mm-dd
//date 为时间对象
function getDateStr3(date) {
  var year = "";
  var month = "";
  var day = "";
  var now = date;
  year = ""+now.getFullYear();
  if((now.getMonth()+1)<10){
    month = "0"+(now.getMonth()+1);
  }else{
    month = ""+(now.getMonth()+1);
  }
  if((now.getDate())<10){
    day = "0"+(now.getDate());
  }else{
    day = ""+(now.getDate());
  }
  return year+"-"+month+"-"+day;
}
/** 
* 获得相对当前周AddWeekCount个周的起止日期 
* AddWeekCount为0代表当前周  为-1代表上一个周  为1代表下一个周以此类推
* **/
function getWeekStartAndEnd(AddWeekCount) { 
  //起止日期数组  
  var startStop = new Array(); 
  //一天的毫秒数  
  var millisecond = 1000 * 60 * 60 * 24; 
  //获取当前时间  
  var currentDate = new Date();
  //相对于当前日期AddWeekCount个周的日期
  currentDate = new Date(currentDate.getTime() + (millisecond * 7*AddWeekCount));
  //返回date是一周中的某一天
  var week = currentDate.getDay(); 
  //返回date是一个月中的某一天  
  var month = currentDate.getDate();
  //减去的天数  
  var minusDay = week != 0 ? week - 1 : 6; 
  //获得当前周的第一天  
  var currentWeekFirstDay = new Date(currentDate.getTime() - (millisecond * minusDay)); 
  //获得当前周的最后一天
   var currentWeekLastDay = new Date(currentWeekFirstDay.getTime() + (millisecond * 6));
  //添加至数组  
  startStop.push(getDateStr3(currentWeekFirstDay)); 
  startStop.push(getDateStr3(currentWeekLastDay)); 
   
  return startStop; 
} 
/** 
* 获得相对当月AddMonthCount个月的起止日期 
* AddMonthCount为0 代表当月 为-1代表上一个月 为1代表下一个月 以此类推
* ***/
function getMonthStartAndEnd(AddMonthCount) { 
  //起止日期数组  
  var startStop = new Array(); 
  //获取当前时间  
  var currentDate = new Date();
  var month=currentDate.getMonth()+AddMonthCount;
  if(month<0){
    var n = parseInt((-month)/12);
    month += n*12;
    currentDate.setFullYear(currentDate.getFullYear()-n);
  }
  currentDate = new Date(currentDate.setMonth(month));
  //获得当前月份0-11  
  var currentMonth = currentDate.getMonth(); 
  //获得当前年份4位年  
  var currentYear = currentDate.getFullYear(); 
  //获得上一个月的第一天  
  var currentMonthFirstDay = new Date(currentYear, currentMonth,1); 
  //获得上一月的最后一天  
  var currentMonthLastDay = new Date(currentYear, currentMonth+1, 0); 
  //添加至数组  
  startStop.push(getDateStr3(currentMonthFirstDay)); 
  startStop.push(getDateStr3(currentMonthLastDay)); 
  //返回  
  return startStop; 
}