js 獲取 本周、上周、本月、上月、本季度、上季度的開始結束日期

/**
 * 獲取本周、本季度、本月、上月的開始日期、結束日期
 */
var now = new Date(); //當前日期
var nowDayOfWeek = now.getDay(); //今天本周的第幾天
var nowDay = now.getDate(); //當前日
var nowMonth = now.getMonth(); //當前月
var nowYear = now.getYear(); //當前年
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);
}
//獲得某月的天數
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;
}
//獲得本季度的開始月份
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;
}
//獲得本周的開始日期
function getWeekStartDate() {
  var weekStartDate = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek);
  return formatDate(weekStartDate);
}
//獲得本周的結束日期
function getWeekEndDate() {
  var weekEndDate = new Date(nowYear, nowMonth, nowDay + (6 - nowDayOfWeek));
  return formatDate(weekEndDate);
}
//獲得上周的開始日期
function getLastWeekStartDate() {
  var weekStartDate = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek - 7);
  return formatDate(weekStartDate);
}
//獲得上周的結束日期
function getLastWeekEndDate() {
  var weekEndDate = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek - 1);
  return formatDate(weekEndDate);
}
//獲得本月的開始日期
function getMonthStartDate() {
  var monthStartDate = new Date(nowYear, nowMonth, 1);
  return formatDate(monthStartDate);
}
//獲得本月的結束日期
function getMonthEndDate() {
  var monthEndDate = new Date(nowYear, nowMonth, getMonthDays(nowMonth));
  return formatDate(monthEndDate);
}
//獲得上月開始時間
function getLastMonthStartDate() {
  var lastMonthStartDate = new Date(nowYear, lastMonth, 1);
  return formatDate(lastMonthStartDate);
}
//獲得上月結束時間
function getLastMonthEndDate() {
  var lastMonthEndDate = new Date(nowYear, lastMonth, getMonthDays(lastMonth));
  return formatDate(lastMonthEndDate);
}
//獲得本季度的開始日期
function getQuarterStartDate() {
  var quarterStartDate = new Date(nowYear, getQuarterStartMonth(), 1);
  return formatDate(quarterStartDate);
}
//或的本季度的結束日期
function getQuarterEndDate() {
  var quarterEndMonth = getQuarterStartMonth() + 2;
  var quarterStartDate = new Date(nowYear, quarterEndMonth,
      getMonthDays(quarterEndMonth));
  return formatDate(quarterStartDate);
}

　　

js 計算月/周的第一天和最后一天

因為項目開發中遇到需要向后台傳本周的開始和結束時間，以及上一周的起止時間，就琢磨了半天，總算寫出來一套，寫篇文章是為了方便自己記憶，也是分享給需要的人，水平有限，寫的不好請見諒：

getDateStr3函數是為了把時間對象轉變為yy-mm-dd的字符串，方便傳值；

getWeekStartAndEnd函數是獲取周的起止時間，並且用getDateStr3轉換成字符串放到數組中，其中參數0代表當前周，-1代表前一周，-2代表上上周，以此類推，反過來也可以1代表下一周；

getMonthStartAndEnd函數是獲取月的起止時間，傳參同上

//獲取當前日期yy-mm-dd
//date 為時間對象
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;
}
/** 
* 獲得相對當前周AddWeekCount個周的起止日期 
* AddWeekCount為0代表當前周  為-1代表上一個周  為1代表下一個周以此類推
* **/
function getWeekStartAndEnd(AddWeekCount) { 
  //起止日期數組  
  var startStop = new Array(); 
  //一天的毫秒數  
  var millisecond = 1000 * 60 * 60 * 24; 
  //獲取當前時間  
  var currentDate = new Date();
  //相對於當前日期AddWeekCount個周的日期
  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是一個月中的某一天  
  var month = currentDate.getDate();
  //減去的天數  
  var minusDay = week != 0 ? week - 1 : 6; 
  //獲得當前周的第一天  
  var currentWeekFirstDay = new Date(currentDate.getTime() - (millisecond * minusDay)); 
  //獲得當前周的最后一天
   var currentWeekLastDay = new Date(currentWeekFirstDay.getTime() + (millisecond * 6));
  //添加至數組  
  startStop.push(getDateStr3(currentWeekFirstDay)); 
  startStop.push(getDateStr3(currentWeekLastDay)); 
   
  return startStop; 
} 
/** 
* 獲得相對當月AddMonthCount個月的起止日期 
* AddMonthCount為0 代表當月 為-1代表上一個月 為1代表下一個月 以此類推
* ***/
function getMonthStartAndEnd(AddMonthCount) { 
  //起止日期數組  
  var startStop = new Array(); 
  //獲取當前時間  
  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));
  //獲得當前月份0-11  
  var currentMonth = currentDate.getMonth(); 
  //獲得當前年份4位年  
  var currentYear = currentDate.getFullYear(); 
  //獲得上一個月的第一天  
  var currentMonthFirstDay = new Date(currentYear, currentMonth,1); 
  //獲得上一月的最后一天  
  var currentMonthLastDay = new Date(currentYear, currentMonth+1, 0); 
  //添加至數組  
  startStop.push(getDateStr3(currentMonthFirstDay)); 
  startStop.push(getDateStr3(currentMonthLastDay)); 
  //返回  
  return startStop; 
}