JS 时间函数

function choseDate(val) {
  Date.prototype.format = function (fmt) {
    var o = {
      'M+': this.getMonth() + 1, //月份 
      'd+': this.getDate(), //日 
      'h+': this.getHours(), //小时 
      'm+': this.getMinutes(), //分 
      's+': this.getSeconds(), //秒 
      'q+': Math.floor((this.getMonth() + 3) / 3), //季度 
      S: this.getMilliseconds(), //毫秒 
    };
    if (/(y+)/.test(fmt)) {
      fmt = fmt.replace(RegExp.$1, (this.getFullYear() + '').substr(4 - RegExp.$1.length));
    }
    for (var k in o) {
      if (new RegExp('(' + k + ')').test(fmt)) {
        fmt = fmt.replace(RegExp.$1, RegExp.$1.length == 1 ? o[k] : ('00' + o[k]).substr(('' + o[k]).length));
      }
    }
    return fmt;
  };
  var params;
  // var date = new Date(); 
  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;
  }
  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;
  }

  function getDay(day) {
    var today = new Date();
    var targetday_milliseconds = today.getTime() + 1000 * 60 * 60 * 24 * day;
    today.setTime(targetday_milliseconds); //注意，这行是关键代码 
    var tYear = today.getFullYear();
    var tMonth = today.getMonth();
    var tDate = today.getDate();
    tMonth = doHandleMonth(tMonth + 1);
    tDate = doHandleMonth(tDate);
    return tYear + '-' + tMonth + '-' + tDate;
  }

  function doHandleMonth(month) {
    var m = month;
    if (month.toString().length == 1) {
      m = '0' + month;
    }
    return m;
  }
  // var flag = parseInt(params); 
  switch (val) {
    case 1:
      // 今日 
      var startStr = now.format('yyyy-MM-dd 00:00:00');
      var endStr = now.format('yyyy-MM-dd 23:59:59');
      params = {
        startDate: startStr,
        endDate: endStr,
      };
      break;
    case 2:
      // 本周 
      var start = getDay(-6);
      var end = getDay(0);
      params = {
        startDate: start + ' 00:00:00',
        endDate: end + ' 23:59:59',
      };
      break;
    case 3:
      // 本月 
      var monthStartDate = new Date(nowYear, nowMonth, 1);
      var start = formatDate(monthStartDate);
      var monthEndDate = new Date(nowYear, nowMonth, getMonthDays(nowMonth));
      var end = formatDate(monthEndDate);
      params = {
        startDate: start + ' 00:00:00',
        endDate: end + ' 23:59:59',
      };
      break;
    case 4:
      // 本季度 
      var quarterStartDate = new Date(nowYear, getQuarterStartMonth(), 1);
      var start = formatDate(quarterStartDate);
      var quarterEndMonth = getQuarterStartMonth() + 2;
      var quarterStartDate = new Date(nowYear, quarterEndMonth, getMonthDays(quarterEndMonth));
      var end = formatDate(quarterStartDate);
      params = {
        startDate: start + ' 00:00:00',
        endDate: end + ' 23:59:59',
      };
      break;
    case 5:
      // 本年 
      var start = now.format('yyyy-01-01 00:00:00');
      var end = now.format('yyyy-12-31 23:59:59');
      params = {
        startDate: start,
        endDate: end,
      };
      break;
    case 6:
      // 昨天 
      var start = getDay(-1);
      var end = getDay(-1);
      params = {
        startDate: start + ' 00:00:00',
        endDate: end + ' 23:59:59',
      };
      break;
    case 7:
      // 上周 
      var start = getDay(-12);
      var end = getDay(-6);
      params = {
        startDate: start + ' 00:00:00',
        endDate: end + ' 23:59:59',
      };
      break;
    case 8:
      // 上月 
      var monthStartDate = new Date(nowYear, nowMonth - 1, 1);
      var start = formatDate(monthStartDate);
      var monthEndDate = new Date(nowYear, nowMonth - 1, getMonthDays(nowMonth - 1));
      var end = formatDate(monthEndDate);
      params = {
        startDate: start + ' 00:00:00',
        endDate: end + ' 23:59:59',
      };
      break;
    case 9:
      // 明日 
      var start = getDay(1);
      var end = getDay(1);
      params = {
        startDate: start + ' 00:00:00',
        endDate: end + ' 23:59:59',
      };
      break;
    case 10:
      // 下周 
      var start = getDay(0);
      var end = getDay(7);
      params = {
        startDate: start + ' 00:00:00',
        endDate: end + ' 23:59:59',
      };
      break;
    case 11:
      // 下月 
      var monthStartDate = new Date(nowYear, nowMonth + 1, 1);
      var start = formatDate(monthStartDate);
      var monthEndDate = new Date(nowYear, nowMonth + 1, getMonthDays(nowMonth + 1));
      var end = formatDate(monthEndDate);
      params = {
        startDate: start + ' 00:00:00',
        endDate: end + ' 23:59:59',
      };
      break;
  }
  return params;
}

// 今日 
console.log('今日', choseDate(1));
// 今日 { startDate: '2020-12-03 00:00:00', endDate: '2020-12-03 23:59:59' } 
// 本周 
console.log('本周', choseDate(2));
// 本周 { startDate: '2020-11-27 00:00:00', endDate: '2020-12-03 23:59:59' } 
// 本月 
console.log('本月', choseDate(3));
// 本月 { startDate: '2020-12-01 00:00:00', endDate: '2020-12-31 23:59:59' } 
console.log('本季度', choseDate(4));
// 本季度 { startDate: '2020-10-01 00:00:00', endDate: '2020-12-31 23:59:59' } 
console.log('本年', choseDate(5));
// 本年 { startDate: '2020-01-01 00:00:00', endDate: '2020-12-31 23:59:59' } 
// 昨日 
console.log('昨日', choseDate(6));
// 昨日 { startDate: '2020-12-02 00:00:00', endDate: '2020-12-02 23:59:59' } 
// 上周 
console.log('上周', choseDate(7));
// 上周 { startDate: '2020-11-21 00:00:00', endDate: '2020-11-27 23:59:59' } 
// 上月 
console.log('上月', choseDate(8));
// 上月 { startDate: '2020-11-01 00:00:00', endDate: '2020-11-30 23:59:59' } 
// 明日 
console.log('明日', choseDate(9));
// 明日 { startDate: '2020-12-04 00:00:00', endDate: '2020-12-04 23:59:59' } 
// 下周 
console.log('下周', choseDate(10));
// 下周 { startDate: '2020-12-03 00:00:00', endDate: '2020-12-10 23:59:59' } 
// 下月 
console.log('下月', choseDate(11));
// 下月 { startDate: '2021-01-01 00:00:00', endDate: '2021-01-31 23:59:59' }