A wave of JavaScript date determination scripts shared

1. Compare the two dates

var x = new Date('2015-05-25'); 
var y = new Date('2015-05-25'); 
 
if (x.getTime() == y.getTime()) { 
 It'll be true; 
} 

2. Whether it is between two dates

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, 1 line of code to determine if it is leap year

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. Judge the status of one week before and after major festivals (National Day, Spring Festival)

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. Determine the day of the week

<SCRIPT> 
var s = '2011-11-17'; 
alert( " What day is it today  "+" day 123456 ".charAt(new Date(s).getDay())); 
alert(" week  " + new Date(s).getDay()); 
</SCRIPT> 

Or it could be:

var weekDay = [" Sunday ", " week 1", " week 2", " week 3", " week 4", " week 5", " week 6"]; 
  var dateStr = "2008-08-08"; 
  var myDate = new Date(Date.parse(dateStr.replace(/-/g, "/"))); 
  alert(weekDay[myDate.getDay()]);