Calculate last day of month in JavaScript

Question

If you provide 0 as the dayValue in Date setFullYear you get the last day of the previous month   d   new Date    d setFullYear 2008  11  0       Sun Nov 30 2008   There is reference to this behaviour at mozilla  Is this a reliable cross-browser feature or should I look at alternative methods

User · Accepted Answer

var month   0     January var d   new Date 2008  month   1  0   alert d      last day in January  IE 6                      Thu Jan 31 00 00 00 CST 2008 IE 7                      Thu Jan 31 00 00 00 CST 2008 IE 8  Beta 2              Thu Jan 31 00 00 00 CST 2008 Opera 8 54                Thu  31 Jan 2008 00 00 00 GMT-0600 Opera 9 27                Thu  31 Jan 2008 00 00 00 GMT-0600 Opera 9 60                Thu Jan 31 2008 00 00 00 GMT-0600 Firefox 2 0 0 17          Thu Jan 31 2008 00 00 00 GMT-0600  Canada Central Standard Time  Firefox 3 0 3             Thu Jan 31 2008 00 00 00 GMT-0600  Canada Central Standard Time  Google Chrome 0 2 149 30  Thu Jan 31 2008 00 00 00 GMT-0600  Canada Central Standard Time  Safari for Windows 3 1 2  Thu Jan 31 2008 00 00 00 GMT-0600  Canada Central Standard Time    Output differences are due to differences in the toString   implementation  not because the dates are different   Of course  just because the browsers identified above use 0 as the last day of the previous month does not mean they will continue to do so  or that browsers not listed will do so  but it lends credibility to the belief that it should work the same way in every browser

User · Answer

function getLastDay y  m       return 30    m  lt   7     m   2    1   0       m   2    1   0   -  m    2  -  m    2  amp  amp  y   4    0      y   100    0  amp  amp  y   400    0

User · Answer

I would use an intermediate date with the first day of the next month  and return the date from the previous day   int d   new Date 2008  11 1 1   d   new Date int d - 1

User · Answer

I recently had to do something similar  this is what I came up with         Returns a date set to the begining of the month       param  Date  myDate     returns  Date     function beginningOfMonth myDate         let date   new Date myDate     date setDate 1    date setHours 0     date setMinutes 0     date setSeconds 0        return date                 Returns a date set to the end of the month         param  Date  myDate      returns  Date      function endOfMonth myDate     let date   new Date myDate     date setMonth date getMonth    1    date setDate 0     date setHours 23     date setMinutes 59     date setSeconds 59     return date      Pass it in a date  and it will return a date set to either the beginning of the month  or the end of the month   The begninngOfMonth function is fairly self-explanatory  but what s going in in the endOfMonth function is that I m incrementing the month to the next month  and then using setDate 0  to roll back the day to the last day of the previous month which is a part of the setDate spec   https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Date setDate https   www w3schools com jsref jsref setdate asp  I then set the hour minutes seconds to the end of the day  so that if you re using some kind of API that is expecting a date range you ll be able to capture the entirety of that last day  That part might go beyond what the original post is asking for but it could help someone else looking for a similar solution   Edit  You can also go the extra mile and set milliseconds with setMilliseconds   if you want to be extra precise

User · Answer

If you need exact end of the month in miliseconds  for example in a timestamp     x000D   x000D  d   new Date   x000D  console log d toString    x000D  d setDate 1  x000D  d setHours 23  59  59  999  x000D  d setMonth d getMonth     1  x000D  d setDate d getDate   - 1  x000D  console log d toString    x000D   x000D   x000D

User · Answer

A slight modification to solution provided by lebreeze   function daysInMonth iMonth  iYear        return new Date iYear  iMonth  0  getDate

User · Answer

Here is an answer that conserves GMT and time of the initial date   x000D   x000D  var date   new Date    x000D   x000D  var first date   new Date date     Make a copy of the date we want the first and last days from x000D  first date setUTCDate 1     Set the day as the first of the month x000D   x000D  var last date   new Date first date     Make a copy of the calculated first day x000D  last date setUTCMonth last date getUTCMonth     1     Add a month x000D  last date setUTCDate 0     Set the date to 0  this goes to the last day of the previous month x000D   x000D  console log first date toJSON   substring 0  10   last date toJSON   substring 0  10      Log the dates with the format yyyy-mm-dd x000D   x000D   x000D

User · Answer

You can get the First and Last Date in the current month by following the code   var dateNow   new Date    var firstDate   new Date dateNow getFullYear    dateNow getMonth    1   var lastDate   new Date dateNow getFullYear    dateNow getMonth     1  0    or if you want to format the date in your custom format then you can use moment js  var dateNow  new Date    var firstDate moment new Date dateNow getFullYear   dateNow getMonth    1   format  quot DD-MM-YYYY quot    var currentDate   moment new Date    format  quot DD-MM-YYYY quot      to  get the current date var lastDate   moment new Date dateNow getFullYear    dateNow getMonth     1  0   format  quot DD-MM-YYYY quot      month last date

User · Answer

This will give you current month first and last day   If you need to change  year  remove d getFullYear   and set your year   If you need to change  month  remove d getMonth   and set your year    x000D   x000D  var d   new Date    x000D  var days     Sunday    Monday    Tuesday    Wednesday    Thursday    Friday    Saturday    x000D  var fistDayOfMonth   days  new Date d getFullYear    d getMonth    1  getDay      x000D   var LastDayOfMonth   days  new Date d getFullYear    d getMonth     1  0  getDay       x000D  console log  First Day      fistDayOfMonth    x000D  console log  Last Day     LastDayOfMonth   x000D  alert  First Day      fistDayOfMonth    x000D  alert  Last Day     LastDayOfMonth   x000D   x000D   x000D

User · Answer

A slight modification to solution provided by lebreeze   function daysInMonth iMonth  iYear        return new Date iYear  iMonth  0  getDate

User · Answer

If you need exact end of the month in miliseconds  for example in a timestamp     x000D   x000D  d   new Date   x000D  console log d toString    x000D  d setDate 1  x000D  d setHours 23  59  59  999  x000D  d setMonth d getMonth     1  x000D  d setDate d getDate   - 1  x000D  console log d toString    x000D   x000D   x000D

User · Answer

The accepted answer doesn t work for me  I did it as below   x000D   x000D     function            datepicker    datepicker          getLastDateOfMon   on  click   function        var date       datepicker   val            Format  mm dd yy  eg  12 31 2018     var parts   date split            var lastDateOfMonth   new Date                    lastDateOfMonth setFullYear parts 2                    lastDateOfMonth setMonth parts 0                    lastDateOfMonth setDate 0         alert lastDateOfMonth toLocaleDateString               x000D   lt  doctype html gt   lt html lang  en  gt   lt head gt     lt meta charset  utf-8  gt     lt meta name  viewport  content  width device-width  initial-scale 1  gt     lt link rel  stylesheet  href    code jquery com ui 1 12 1 themes base jquery-ui css  gt     lt link rel  stylesheet  href   resources demos style css  gt     lt script src  https   code jquery com jquery-1 12 4 js  gt  lt  script gt     lt script src  https   code jquery com ui 1 12 1 jquery-ui js  gt  lt  script gt   lt  head gt   lt body gt     lt p gt Date   lt input type  text  id  datepicker  gt  lt  p gt   lt button id  getLastDateOfMon  gt Get Last Date of Month  lt  button gt       lt  body gt   lt  html gt  x000D   x000D   x000D

User · Answer

I know it s just a matter of semantics  but I ended up using it in this form    var lastDay   new Date new Date 2008  11 1 1  - 1  getDate    console log lastDay     Since functions are resolved from the inside argument  outward  it works the same    You can then just replace the year  and month   year with the required details  whether it be from the current date  Or a particular month   year

User · Answer

In computer terms  new Date   and regular expression solutions are slow  If you want a super-fast  and super-cryptic  one-liner  try this one  assuming m is in Jan 1 format   I keep trying different code changes to get the best performance   My current fastest version   After looking at this related question Leap year check using bitwise operators  amazing speed  and discovering what the 25  amp  15 magic number represented  I have come up with this optimized hybrid of answers   function getDaysInMonth m  y        return m   2   y  amp  3      y 25   amp  amp  y  amp  15   28   29   30    m  m gt  gt 3  amp 1       Given the bit-shifting this obviously assumes that your m  amp  y parameters are both integers  as passing numbers as strings would result in weird results   JSFiddle  http   jsfiddle net TrueBlueAussie H89X3 22   JSPerf results  http   jsperf com days-in-month-head-to-head 5  For some reason   m  m gt  gt 3  amp 1  is more efficient than  5546 gt  gt m amp 1  on almost all browsers   The only real competition for speed is from  GitaarLab  so I have created a head-to-head JSPerf for us to test on  http   jsperf com days-in-month-head-to-head 5    It works based on my leap year answer here  javascript to find leap year this answer here Leap year check using bitwise operators  amazing speed  as well as the following binary logic   A quick lesson in binary months   If you interpret the index of the desired months  Jan   1  in binary you will notice that months with 31 days either have bit 3 clear and bit 0 set  or bit 3 set and bit 0 clear   Jan   1    0001   31 days Feb   2    0010 Mar   3    0011   31 days Apr   4    0100 May   5    0101   31 days Jun   6    0110 Jul   7    0111   31 days Aug   8    1000   31 days Sep   9    1001 Oct   10   1010   31 days Nov   11   1011 Dec   12   1100   31 days   That means you can shift the value 3 places with  gt  gt  3  XOR the bits with the original   m and see if the result is 1 or 0 in bit position 0 using  amp  1  Note  It turns out   is slightly faster than XOR     and  m  gt  gt  3    m gives the same result in bit 0   JSPerf results  http   jsperf com days-in-month-perf-test 6

User · Answer

This works for me  Will provide last day of given year and month   var d   new Date 2012 02 0   var n   d getDate    alert n

User · Answer

Below function gives the last day of the month     x000D   x000D  function getLstDayOfMonFnc date    x000D    return new Date date getFullYear    date getMonth    0  getDate   x000D    x000D   x000D  console log getLstDayOfMonFnc new Date 2016  2  15       Output   29 x000D  console log getLstDayOfMonFnc new Date 2017  2  15       Output   28 x000D  console log getLstDayOfMonFnc new Date 2017  11  15       Output   30 x000D  console log getLstDayOfMonFnc new Date 2017  12  15       Output   31 x000D   x000D   x000D    Similarly we can get first day of the month     x000D   x000D  function getFstDayOfMonFnc date    x000D    return new Date date getFullYear    date getMonth    1  getDate   x000D    x000D   x000D  console log getFstDayOfMonFnc new Date 2016  2  15       Output   1 x000D   x000D   x000D

User · Answer

const today   new Date     let beginDate   new Date     let endDate   new Date        fist date of montg  beginDate   new Date        today getFullYear   -  today getMonth     1 -01 00 00 00          end date of month      set next Month first Date  endDate   new Date        today getFullYear   -  today getMonth     2 -01  23 59 59          deducting 1 day  endDate setDate 0

User · Answer

My colleague stumbled upon the following which may be an easier solution  function daysInMonth iMonth  iYear        return 32 - new Date iYear  iMonth  32  getDate        stolen from http   snippets dzone com posts show 2099

User · Answer

set month you need to date and then set the day to zero  so month begin in 1 - 31 in date function then get the last day     x000D   x000D  var last   new Date new Date new Date   setMonth 7   setDate 0   getDate    x000D  console log last   x000D   x000D   x000D

User · Answer

set month you need to date and then set the day to zero  so month begin in 1 - 31 in date function then get the last day     x000D   x000D  var last   new Date new Date new Date   setMonth 7   setDate 0   getDate    x000D  console log last   x000D   x000D   x000D

User · Answer

Try this   function  getEndOfMonth time stamp        let time   new Date time stamp   1000       let month   time getMonth     1      let year   time getFullYear        let day   time getDate        switch  month            case 1          case 3          case 5          case 7          case 8          case 10          case 12              day   31              break          case 4          case 6          case 9          case 11              day   30              break          case 2              if   leapyear year                   day   29              else                 day   28              break           let m   moment    year -  month -  day     YYYY-MM-DD       return m unix     constants DAY - 1     function  leapyear year        return  year   100     0     year   400     0     year   4     0

User · Answer

Try this   function  getEndOfMonth time stamp        let time   new Date time stamp   1000       let month   time getMonth     1      let year   time getFullYear        let day   time getDate        switch  month            case 1          case 3          case 5          case 7          case 8          case 10          case 12              day   31              break          case 4          case 6          case 9          case 11              day   30              break          case 2              if   leapyear year                   day   29              else                 day   28              break           let m   moment    year -  month -  day     YYYY-MM-DD       return m unix     constants DAY - 1     function  leapyear year        return  year   100     0     year   400     0     year   4     0

User · Answer

I find this to be the best solution for me  Let the Date object calculate it for you   var today   new Date    var lastDayOfMonth   new Date today getFullYear    today getMonth   1  0     Setting day parameter to 0 means one day less than first day of the month which is last day of the previous month

User · Answer

Below function gives the last day of the month     x000D   x000D  function getLstDayOfMonFnc date    x000D    return new Date date getFullYear    date getMonth    0  getDate   x000D    x000D   x000D  console log getLstDayOfMonFnc new Date 2016  2  15       Output   29 x000D  console log getLstDayOfMonFnc new Date 2017  2  15       Output   28 x000D  console log getLstDayOfMonFnc new Date 2017  11  15       Output   30 x000D  console log getLstDayOfMonFnc new Date 2017  12  15       Output   31 x000D   x000D   x000D    Similarly we can get first day of the month     x000D   x000D  function getFstDayOfMonFnc date    x000D    return new Date date getFullYear    date getMonth    1  getDate   x000D    x000D   x000D  console log getFstDayOfMonFnc new Date 2016  2  15       Output   1 x000D   x000D   x000D

User · Answer

You can get the First and Last Date in the current month by following the code   var dateNow   new Date    var firstDate   new Date dateNow getFullYear    dateNow getMonth    1   var lastDate   new Date dateNow getFullYear    dateNow getMonth     1  0    or if you want to format the date in your custom format then you can use moment js  var dateNow  new Date    var firstDate moment new Date dateNow getFullYear   dateNow getMonth    1   format  quot DD-MM-YYYY quot    var currentDate   moment new Date    format  quot DD-MM-YYYY quot      to  get the current date var lastDate   moment new Date dateNow getFullYear    dateNow getMonth     1  0   format  quot DD-MM-YYYY quot      month last date

User · Answer

This works for me  Will provide last day of given year and month   var d   new Date 2012 02 0   var n   d getDate    alert n

User · Answer

try this one    lastDateofTheMonth   new Date year  month  0    example   new Date 2012  8  0    output   Date  Fri Aug 31 2012 00 00 00 GMT 0900  Tokyo Standard Time

User · Answer

This one works nicely   Date prototype setToLastDateInMonth   function           this setDate 1       this setMonth this getMonth     1       this setDate this getDate   - 1        return this

User · Answer

In computer terms  new Date   and regular expression solutions are slow  If you want a super-fast  and super-cryptic  one-liner  try this one  assuming m is in Jan 1 format   I keep trying different code changes to get the best performance   My current fastest version   After looking at this related question Leap year check using bitwise operators  amazing speed  and discovering what the 25  amp  15 magic number represented  I have come up with this optimized hybrid of answers   function getDaysInMonth m  y        return m   2   y  amp  3      y 25   amp  amp  y  amp  15   28   29   30    m  m gt  gt 3  amp 1       Given the bit-shifting this obviously assumes that your m  amp  y parameters are both integers  as passing numbers as strings would result in weird results   JSFiddle  http   jsfiddle net TrueBlueAussie H89X3 22   JSPerf results  http   jsperf com days-in-month-head-to-head 5  For some reason   m  m gt  gt 3  amp 1  is more efficient than  5546 gt  gt m amp 1  on almost all browsers   The only real competition for speed is from  GitaarLab  so I have created a head-to-head JSPerf for us to test on  http   jsperf com days-in-month-head-to-head 5    It works based on my leap year answer here  javascript to find leap year this answer here Leap year check using bitwise operators  amazing speed  as well as the following binary logic   A quick lesson in binary months   If you interpret the index of the desired months  Jan   1  in binary you will notice that months with 31 days either have bit 3 clear and bit 0 set  or bit 3 set and bit 0 clear   Jan   1    0001   31 days Feb   2    0010 Mar   3    0011   31 days Apr   4    0100 May   5    0101   31 days Jun   6    0110 Jul   7    0111   31 days Aug   8    1000   31 days Sep   9    1001 Oct   10   1010   31 days Nov   11   1011 Dec   12   1100   31 days   That means you can shift the value 3 places with  gt  gt  3  XOR the bits with the original   m and see if the result is 1 or 0 in bit position 0 using  amp  1  Note  It turns out   is slightly faster than XOR     and  m  gt  gt  3    m gives the same result in bit 0   JSPerf results  http   jsperf com days-in-month-perf-test 6

User · Answer

const today   new Date     let beginDate   new Date     let endDate   new Date        fist date of montg  beginDate   new Date        today getFullYear   -  today getMonth     1 -01 00 00 00          end date of month      set next Month first Date  endDate   new Date        today getFullYear   -  today getMonth     2 -01  23 59 59          deducting 1 day  endDate setDate 0

User · Answer

I recently had to do something similar  this is what I came up with         Returns a date set to the begining of the month       param  Date  myDate     returns  Date     function beginningOfMonth myDate         let date   new Date myDate     date setDate 1    date setHours 0     date setMinutes 0     date setSeconds 0        return date                 Returns a date set to the end of the month         param  Date  myDate      returns  Date      function endOfMonth myDate     let date   new Date myDate     date setMonth date getMonth    1    date setDate 0     date setHours 23     date setMinutes 59     date setSeconds 59     return date      Pass it in a date  and it will return a date set to either the beginning of the month  or the end of the month   The begninngOfMonth function is fairly self-explanatory  but what s going in in the endOfMonth function is that I m incrementing the month to the next month  and then using setDate 0  to roll back the day to the last day of the previous month which is a part of the setDate spec   https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Date setDate https   www w3schools com jsref jsref setdate asp  I then set the hour minutes seconds to the end of the day  so that if you re using some kind of API that is expecting a date range you ll be able to capture the entirety of that last day  That part might go beyond what the original post is asking for but it could help someone else looking for a similar solution   Edit  You can also go the extra mile and set milliseconds with setMilliseconds   if you want to be extra precise

User · Answer

I would use an intermediate date with the first day of the next month  and return the date from the previous day   int d   new Date 2008  11 1 1   d   new Date int d - 1

User · Answer

I would use an intermediate date with the first day of the next month  and return the date from the previous day   int d   new Date 2008  11 1 1   d   new Date int d - 1

User · Answer

Here is an answer that conserves GMT and time of the initial date   x000D   x000D  var date   new Date    x000D   x000D  var first date   new Date date     Make a copy of the date we want the first and last days from x000D  first date setUTCDate 1     Set the day as the first of the month x000D   x000D  var last date   new Date first date     Make a copy of the calculated first day x000D  last date setUTCMonth last date getUTCMonth     1     Add a month x000D  last date setUTCDate 0     Set the date to 0  this goes to the last day of the previous month x000D   x000D  console log first date toJSON   substring 0  10   last date toJSON   substring 0  10      Log the dates with the format yyyy-mm-dd x000D   x000D   x000D

User · Answer

This will give you current month first and last day   If you need to change  year  remove d getFullYear   and set your year   If you need to change  month  remove d getMonth   and set your year    x000D   x000D  var d   new Date    x000D  var days     Sunday    Monday    Tuesday    Wednesday    Thursday    Friday    Saturday    x000D  var fistDayOfMonth   days  new Date d getFullYear    d getMonth    1  getDay      x000D   var LastDayOfMonth   days  new Date d getFullYear    d getMonth     1  0  getDay       x000D  console log  First Day      fistDayOfMonth    x000D  console log  Last Day     LastDayOfMonth   x000D  alert  First Day      fistDayOfMonth    x000D  alert  Last Day     LastDayOfMonth   x000D   x000D   x000D

User · Answer

I know it s just a matter of semantics  but I ended up using it in this form    var lastDay   new Date new Date 2008  11 1 1  - 1  getDate    console log lastDay     Since functions are resolved from the inside argument  outward  it works the same    You can then just replace the year  and month   year with the required details  whether it be from the current date  Or a particular month   year

User · Answer

I would use an intermediate date with the first day of the next month  and return the date from the previous day   int d   new Date 2008  11 1 1   d   new Date int d - 1

User · Answer

My colleague stumbled upon the following which may be an easier solution  function daysInMonth iMonth  iYear        return 32 - new Date iYear  iMonth  32  getDate        stolen from http   snippets dzone com posts show 2099

User · Answer

try this one    lastDateofTheMonth   new Date year  month  0    example   new Date 2012  8  0    output   Date  Fri Aug 31 2012 00 00 00 GMT 0900  Tokyo Standard Time

User · Answer

This one works nicely   Date prototype setToLastDateInMonth   function           this setDate 1       this setMonth this getMonth     1       this setDate this getDate   - 1        return this

User · Answer

The accepted answer doesn t work for me  I did it as below   x000D   x000D     function            datepicker    datepicker          getLastDateOfMon   on  click   function        var date       datepicker   val            Format  mm dd yy  eg  12 31 2018     var parts   date split            var lastDateOfMonth   new Date                    lastDateOfMonth setFullYear parts 2                    lastDateOfMonth setMonth parts 0                    lastDateOfMonth setDate 0         alert lastDateOfMonth toLocaleDateString               x000D   lt  doctype html gt   lt html lang  en  gt   lt head gt     lt meta charset  utf-8  gt     lt meta name  viewport  content  width device-width  initial-scale 1  gt     lt link rel  stylesheet  href    code jquery com ui 1 12 1 themes base jquery-ui css  gt     lt link rel  stylesheet  href   resources demos style css  gt     lt script src  https   code jquery com jquery-1 12 4 js  gt  lt  script gt     lt script src  https   code jquery com ui 1 12 1 jquery-ui js  gt  lt  script gt   lt  head gt   lt body gt     lt p gt Date   lt input type  text  id  datepicker  gt  lt  p gt   lt button id  getLastDateOfMon  gt Get Last Date of Month  lt  button gt       lt  body gt   lt  html gt  x000D   x000D   x000D

User · Answer

function getLastDay y  m       return 30    m  lt   7     m   2    1   0       m   2    1   0   -  m    2  -  m    2  amp  amp  y   4    0      y   100    0  amp  amp  y   400    0

User · Answer

I find this to be the best solution for me  Let the Date object calculate it for you   var today   new Date    var lastDayOfMonth   new Date today getFullYear    today getMonth   1  0     Setting day parameter to 0 means one day less than first day of the month which is last day of the previous month

[javascript] Calculate last day of month in JavaScript

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