一波JavaScript日期判断脚本分享

1、比较两个日期先后

var x = new Date('2015-05-25');
var y = new Date('2015-05-25'); 

if (x.getTime() == y.getTime()) {
 It'll be true;
}

2、是否在两个日期之间  

var beforeSpringDate, afterSpringDate;
 for (var i = 0; i < springFestivalDays.length; i++) {
 beforeSpringDate = new Date(springFestivalDays[i]);
 beforeSpringDate.setDate(beforeSpringDate.getDate() - 4);
 afterSpringDate = new Date(springFestivalDays[i]);
 afterSpringDate.setDate(afterSpringDate.getDate() + springFestivalPeriod - 1);
 if (time >= beforeSpringDate.getTime() && time <= afterSpringDate.getTime()) {
  result = true;
  break;
 }
 } 

3、一行代码判断是否是闰年

var input = new Date();new Date(input.getFullYear(), 1, 29).getDate() === 29
false 

var input = new Date(2012,1,1);new Date(input.getFullYear(), 1, 29).getDate() === 29
true 

var input = new Date(2013,1,1);new Date(input.getFullYear(), 1, 29).getDate() === 29
false 

var input = new Date(2014,1,1);new Date(input.getFullYear(), 1, 29).getDate() === 29
false 

var input = new Date(2014,5,1);new Date(input.getFullYear(), 1, 29).getDate() === 29
false 

var input = new Date(2014,6,1);new Date(input.getFullYear(), 1, 29).getDate() === 29
false 

var input = new Date(2016,6,1);new Date(input.getFullYear(), 1, 29).getDate() === 29
true 

var input = new Date(2000,6,1);new Date(input.getFullYear(), 1, 29).getDate() === 29
true

4、判断重大节日(国庆、春节)前后一周状态

var holiday = {}; 

function inNationalDay(date) {
 var result = {
 beforeNationalDay: false,
 duringNationalDay: false
 };
 if (date) {
 var month = date.getMonth() + 1,
  day = date.getDate();
 if (month == 9 && (day >= 24 && day <= 30)) {
  result.beforeNationalDay = true;
 } else if(month == 10 && (day >= 1 && day <= 7)) {
  result.duringNationalDay = true;
 }
 }
 return result;
} 

function inSpringFestival(date) {
 var result = {
 beforeSpringFestival: false,
 duringSpringFestival: false
 };
 if (date) {
 // set GMT+0800 hours(set china hour +8)
 date = new Date(date.getFullYear(), date.getMonth(), date.getDate(), 8);
 var time = date.getTime();
 var springFestivalDays = ['2015-02-19', '2016-02-08', '2017-01-28', '2018-02-16', '2019-02-05',
  '2020-01-25', '2021-02-12', '2022-02-01', '2023-01-22', '2024-02-10']; 

 var springDay, springDate, beforeSpringDate, afterSpringDate;
 for (var i = 0; i < springFestivalDays.length; i++) {
  springDay = springFestivalDays[i];
  springDate = new Date(springDay);
  beforeSpringDate = new Date(springDay);
  beforeSpringDate.setDate(beforeSpringDate.getDate() - 7);
  afterSpringDate = new Date(springDay);
  afterSpringDate.setDate(afterSpringDate.getDate() + 7);
  if (time >= beforeSpringDate.getTime() && time < springDate.getTime()) {
  result.beforeSpringFestival = true;
  break;
  } else if (time >= springDate.getTime() && time < afterSpringDate.getTime()) {
  result.duringSpringFestival = true;
  break;
  }
 }
 } 

 return result;
} 

holiday.cache = {
 lastUpdateDate: null,
 beforeHoliday: false,
 duringHoliday: false
}; 

holiday.checkHoliday = function() {
 var now = new Date();
 if (!holiday.cache.lastUpdateDate) {
 holiday.cache.lastUpdateDate = now;
 var nationalDayResult = inNationalDay(now);
 var springFestivalResult = inSpringFestival(now);
 holiday.cache.beforeHoliday = nationalDayResult.beforeNationalDay || springFestivalResult.beforeSpringFestival;
 holiday.cache.duringHoliday = nationalDayResult.duringNationalDay || springFestivalResult.duringSpringFestival;
 } else {
 var lastUpdateDate = holiday.cache.lastUpdateDate;
 var cacheDate = lastUpdateDate.getFullYear() + '' + lastUpdateDate.getMonth() + '' + lastUpdateDate.getDate();
 var nowDate = now.getFullYear() + '' + now.getMonth() + '' + now.getDate();
 if (cacheDate != nowDate) {
  holiday.cache.lastUpdateDate = now;
  var nationalDayResult = inNationalDay(now);
  var springFestivalResult = inSpringFestival(now);
  holiday.cache.beforeHoliday = nationalDayResult.beforeNationalDay || springFestivalResult.beforeSpringFestival;
  holiday.cache.duringHoliday = nationalDayResult.duringNationalDay || springFestivalResult.duringSpringFestival;
 }
 }
}; 

module.exports = holiday;

5、判断星期几

<SCRIPT>
var s = '2011-11-17';
alert( "今天星期 "+"天一二三四五六 ".charAt(new Date(s).getDay()));
alert("星期 " + new Date(s).getDay());
</SCRIPT>

也可以这样：

var weekDay = ["星期天", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"];
  var dateStr = "2008-08-08";
  var myDate = new Date(Date.parse(dateStr.replace(/-/g, "/")));
  alert(weekDay[myDate.getDay()]);