How do I calculate the date in JavaScript three months prior to today

Question

I Am trying to form a date which is 3 months before the current date  I get the current month by the below code  var currentDate   new Date    var currentMonth   currentDate getMonth   1    Can you guys provide me the logic to calculate and form a date  an object of the Date data type  considering that when the month is January  1   3 months before date would be OCtober  10

User · Answer

As I don t seem to see it already suggested     const d   new Date    const day   d getDate    const goBack   3  for  let i   0  i  lt  goBack  i    d setDate 0   d setDate day    This will give you the date of today s date 3 months ago as  setDate 0  sets the date to the last day of last month irrespective of how many days a month contains   day is used to restore today s date value

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This is the Smallest and easiest code      var minDate   new Date        minDate setMonth minDate getMonth   - 3     Declare variable which has current date  then just by using setMonth inbuilt function we can get 3 month back date

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var d   new Date    d setMonth d getMonth   - 3     This works for January   Run this snippet    x000D   x000D  var d   new Date  January 14  2012    x000D  console log d toLocaleDateString     x000D  d setMonth d getMonth   - 3   x000D  console log d toLocaleDateString     x000D   x000D   x000D      There are some caveats     A month is a curious thing   How do you define 1 month   30 days   Most people will say that one month ago means the same day of the month on the previous month citation needed   But more than half the time  that is 31 days ago  not 30   And if today is the 31st of the month  and it isn t August or Decemeber   that day of the month doesn t exist in the previous month   Interestingly  Google agrees with JavaScript if you ask it what day is one month before another day     It also says that one month is 30 4167 days long    So  is one month before March 31st the same day as one month before March 28th  3 days earlier   This all depends on what you mean by  one month before    Go have a conversation with your product owner   If you want to do like momentjs does  and correct these last day of the month errors by moving to the last day of the month  you can do something like this    x000D   x000D  const d   new Date  March 31  2019    x000D  console log d toLocaleDateString     x000D  const month   d getMonth    x000D  d setMonth d getMonth   - 1   x000D  while  d getMonth       month    x000D      d setDate d getDate   - 1   x000D    x000D  console log d toLocaleDateString     x000D   x000D   x000D    If your requirements are more complicated than that  use some math and write some code   You are a developer   You don t have to install a library   You don t have to copy and paste from stackoverflow   You can develop the code yourself to do precisely what you need

User · Answer

x000D   x000D  var d   new Date  2013 01 01    x000D  console log d toLocaleDateString     x000D  d setMonth d getMonth     18   x000D  console log d toLocaleDateString     x000D   x000D   x000D

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x000D   x000D      x000D   x000D   var date document getElementById  date    x000D      var d   new Date    x000D     document write d     lt br  gt     x000D      d setMonth d getMonth   - 6   x000D      document write d   x000D   x000D   if d lt date  x000D    document write  lesser then 6 months    x000D  else x000D    document write  greater then 6 months    x000D   x000D   x000D

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x000D   x000D  var d   new Date    x000D  document write d     lt br  gt     x000D  d setMonth d getMonth   - 6   x000D  document write d   x000D   x000D   x000D

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Pass a JS Date object and an integer of how many months you want to add subtract  monthsToAdd can be positive or negative  Returns a JS date object   If your originalDateObject is March 31  and you pass -1 as monthsToAdd  then your output date will be February 28   If you pass a large number of months  say 36  it will handle the year adjustment properly as well   const addMonthsToDate    originalDateObject  monthsToAdd    gt      const originalDay   originalDateObject getUTCDate      const originalMonth   originalDateObject getUTCMonth      const originalYear   originalDateObject getUTCFullYear       const monthDayCountMap          0   31       1   28       2   31       3   30       4   31       5   30       6   31       7   31       8   30       9   31       10   30       11   31         let newMonth    if  newMonth  gt  -1        newMonth      originalMonth   monthsToAdd    12   toString        else       const delta    monthsToAdd   -1    12      newMonth   originalMonth - delta  lt  0    12 originalMonth  - delta   originalMonth - delta         let newDay     if  originalDay  gt  monthDayCountMap newMonth         newDay   monthDayCountMap newMonth  toString        else       newDay   originalDay toString           newMonth     newMonth   1  toString       if  newMonth length     1        newMonth    0    newMonth         if  newDay length     1        newDay    0    newDay         if  monthsToAdd  lt   0        monthsToAdd -  11         let newYear        originalMonth   monthsToAdd    12     originalYear     let newTime   originalDateObject toISOString   slice 10  24      const newDateISOString      newYear -  newMonth -  newDay   newTime       return new Date newDateISOString

User · Answer

If the setMonth method offered by gilly3 isn t what you re looking for  consider   var someDate   new Date       add arguments as needed someDate setTime someDate getTime   - 3 28 24 60 60      assumes the definition of  one month  to be  four weeks     Can be used for any amount of time  just set the right multiples

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A  one liner   on many line for easy read   to be put directly into a variable   var oneMonthAgo   new Date      new Date   getFullYear        new Date   getMonth   - 1       new Date   getDate

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Do this  let currentdate   new Date     let last3months   new Date currentdate setMonth currentdate getMonth  -3     Javascript s setMonth method also takes care of the year  For instance  the above code will return 2020-01-29 if currentDate is set as new Date  quot 2020-01-29 quot

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I recommend using a library called Moment js    It is well tested  works cross browser and on server side I am using it both in Angular and Node projects   It has great support for locale dates    http   momentjs com   var threeMonthsAgo   moment   subtract 3   months     console log threeMonthsAgo format        2015-10-13T09 37 35 02 00    format   returns string representation of date formatted in ISO 8601 format  You can also use it with custom date format like this  format  dddd  MMMM Do YYYY  h mm ss a

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I like the simplicity of gilly3 s answer  but users will probably be surprised that a month before March 31 is March 3  I chose to implement a version that sticks to the end of the month  so a month before March 28  29  30  and 31 will all be Feb 28 when it s not a leap year    x000D   x000D  function addMonths date  months    x000D    var result   new Date date   x000D        expectedMonth     date getMonth     months    12   12    12  x000D    result setMonth result getMonth     months   x000D    if  result getMonth       expectedMonth    x000D      result setDate 0   x000D      x000D    return result  x000D    x000D   x000D  var dt2004 05 31   new Date  2004-05-31 0 00    x000D      dt2001 05 31   new Date  2001-05-31 0 00    x000D      dt2001 03 31   new Date  2001-03-31 0 00    x000D      dt2001 02 28   new Date  2001-02-28 0 00    x000D      result   addMonths dt2001 05 31  -2   x000D  console assert dt2001 03 31 getTime      result getTime    result toDateString     x000D   x000D  result   addMonths dt2001 05 31  -3   x000D  console assert dt2001 02 28 getTime      result getTime    result toDateString     x000D   x000D  result   addMonths dt2001 05 31  36   x000D  console assert dt2004 05 31 getTime      result getTime    result toDateString     x000D   x000D  result   addMonths dt2004 05 31  -38   x000D  console assert dt2001 03 31 getTime      result getTime    result toDateString     x000D   x000D  console log  Done     x000D   x000D   x000D

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This should handle addition subtraction  just put a negative value in to subtract and a positive value to add  This also solves the month crossover problem   function monthAdd date  month        var temp   date      temp   new Date date getFullYear    date getMonth    1       temp setMonth temp getMonth      month   1        temp setDate temp getDate   - 1         if  date getDate    lt  temp getDate               temp setDate date getDate                 return temp

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To make things really simple you can use DateJS  a date library for JavaScript   http   www datejs com   Example code for you   Date today   add   months  -1

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Following code give me Just Previous Month From Current Month even the date is 31 30 of current date and last month is 30 29 28 days       lt  DOCTYPE html gt   lt html gt   lt body gt    lt p gt Click the button to display the date after changing the month  lt  p gt    lt button onclick  myFunction    gt Try it lt  button gt    lt p id  demo  gt  lt  p gt    lt script gt  function myFunction      var d   new Date  March 29  2017       Please Try the result also for  March 31  2017  Or  March 30  2017  var OneMonthBefore  new Date d    OneMonthBefore setMonth d getMonth   0   if OneMonthBefore getDate    lt  d getDate        d setMonth d getMonth   0    else   d setMonth d getMonth  -1           document getElementById  demo   innerHTML   d     lt  script gt    lt  body gt   lt  html gt

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In my case I needed to substract 1 month to current date  The important part was the month number  so it doesn t care in which day of the current month you are at  I needed last month  This is my code   var dateObj   new Date  2017-03-30 00 00 00      Create new date object console log dateObj      Thu Mar 30 2017 00 00 00 GMT-0300  ART   dateObj setDate 1     Set first day of the month from current date dateObj setDate -1      Substract 1 day to the first day of the month    Now  you are in the last month console log dateObj      Mon Feb 27 2017 00 00 00 GMT-0300  ART    Substract 1 month to actual date it s not accurate  that s why in first place I set first day of the month  first day of any month always is first day  and in second place I substract 1 day  which always send you to last month  Hope to help you dude    x000D   x000D  var dateObj   new Date  2017-03-30 00 00 00      Create new date object x000D  console log dateObj      Thu Mar 30 2017 00 00 00 GMT-0300  ART  x000D   x000D  dateObj setDate 1     Set first day of the month from current date x000D  dateObj setDate -1      Substract 1 day to the first day of the month x000D   x000D    Now  you are in the last month x000D  console log dateObj      Mon Feb 27 2017 00 00 00 GMT-0300  ART  x000D   x000D   x000D

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There is an elegant answer already but I find that its hard to read so I made my own function  For my purposes I didn t need a negative result but it wouldn t be hard to modify       var subtractMonths   function  date1 date2            if  date1-date2  lt  0                return 0                    var monthCount   0          while  date1  gt  date2               monthCount                date1 setMonth date1 getMonth   -1                     return monthCount

[javascript] How do I calculate the date in JavaScript three months prior to today?

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