How to validate a date

Question

I m trying to test to make sure a date is valid in the sense that if someone enters 2 30 2011 then it should be wrong   How can I do this with any date

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Hi Please find the answer below this is done by validating the date newly created  var year 2019  var month 2  var date 31  var d   new Date year  month - 1  date   if  d getFullYear      year            d getMonth       month - 1             d getDate      date        alert  invalid date        return false

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My function returns true if is a valid date otherwise returns false  D   x000D   x000D  function isDate   day  month  year   x000D   if day    0    x000D    return false  x000D     x000D   switch month   x000D    case 1  case 3  case 5  case 7  case 8  case 10  case 12  x000D     if day  gt  31  x000D      return false  x000D     return true  x000D    case 2  x000D     if  year   4    0  x000D      if day  gt  29   x000D       return false  x000D        x000D      else  x000D       return true  x000D        x000D     if day  gt  28   x000D      return false  x000D       x000D     return true  x000D    case 4  case 6  case 9  case 11  x000D     if day  gt  30   x000D      return false  x000D       x000D     return true  x000D    default  x000D     return false  x000D     x000D    x000D   x000D  console log isDate 30  5  2017    x000D  console log isDate 29  2  2016    x000D  console log isDate 29  2  2015    x000D   x000D   x000D

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Though this was raised long ago  still a most wanted validation  I found an interesting blog with few function     Please use these function to check the reuslt only  do not check for otherewise  other than utiljs isInvalidDate  Ex -  utiljs isFutureDate   retuns only true for future dates  false does not mean it is not future date  it may be an invalid date   practice    call utiljs isInvalidDate first and then use the returned date for utiljs isFutureDate    var d        if  utiljs isInvalidDate  32 02 2012   d    if utiljs isFutureDate d      date is a future date  else     date is not a future date         function utiljs isInvalidDate dateStr  returnDate           dateStr   format should be dd mm yyyy  Ex - 31 10 2017        returnDate will be in  date js date object          Ex - if you only need to check whether the date is invalid          utiljs isInvalidDate  03 03 2017          Ex - if need the date  if the date is valid          var dt               if  utiljs isInvalidDate  03 03 2017   dt               you can use dt date                         if   dateStr          return true      if   dateStr substring     dateStr length    dateStr length    10          return true      var day   parseInt dateStr substring 0  2   10       var month   parseInt dateStr substring 3  5   10       var year   parseInt dateStr substring 6   10       var fullString   dateStr substring 0  2    dateStr substring 3  5    dateStr substring 6       if  null    fullString match    d        to check for whether there are only numbers         return true      var dt   new Date month    quot   quot    day    quot   quot    year       if  dt     Invalid Date     isNaN dt       if the date string is not valid  new Date will create this string instead         return true            if  dt getFullYear      year    dt getMonth     1    month    dt getDate      day    to avoid 31 02 2018 like dates         return true      if  returnDate          returnDate date   dt      return false     function utiljs isFutureDate dateStrOrObject  returnDate        return utiljs isFuturePast dateStrOrObject  returnDate  true      function utiljs isPastDate dateStrOrObject  returnDate        return utiljs isFuturePast dateStrOrObject  returnDate  false      function utiljs isValidDateObjectOrDateString dateStrOrObject  returnDate      this is an internal function     var dt           if   dateStrOrObject          return false      if  typeof dateStrOrObject getMonth      function           dt date   new Date dateStrOrObject     to avoid modifying original date     else if  utiljs isInvalidDate dateStrOrObject  dt           return false      if  returnDate          returnDate date   dt date      return true      function utiljs isFuturePast dateStrOrObject  returnDate  isFuture      this is an internal function  please use isFutureDate or isPastDate function     if   dateStrOrObject          return false      var dt           if   utiljs isValidDateObjectOrDateString dateStrOrObject  dt           return false      today   new Date        today setHours 0  0  0  0       if  dt date          dt date setHours 0  0  0  0       if  returnDate          returnDate date   dt date        creating new date using only current d m y  as td date is created with string  otherwise same day selection will not be validated      if  isFuture  amp  amp  dt date  amp  amp  dt date getTime  amp  amp  dt date getTime    gt  today getTime              return true            if   isFuture  amp  amp  dt date  amp  amp  dt date getTime  amp  amp  dt date getTime    lt  today getTime              return true            return false     function utiljs isLeapYear dateStrOrObject  returnDate        var dt           if   dateStrOrObject          return false      if  utiljs isValidDateObjectOrDateString dateStrOrObject  dt             if  returnDate              returnDate date   dt date          return dt date getFullYear     4    0            return false     function utiljs firstDateLaterThanSecond firstDate  secondDate  returnFirstDate  returnSecondDate        if   firstDate     secondDate          return false      var dt1           dt2           if   utiljs isValidDateObjectOrDateString firstDate  dt1      utiljs isValidDateObjectOrDateString secondDate  dt2           return false      if  returnFirstDate          returnFirstDate date   dt1 date      if  returnSecondDate          returnSecondDate date   dt2 date      dt1 date setHours 0  0  0  0       dt2 date setHours 0  0  0  0       if  dt1 date getTime  amp  amp  dt2 date getTime  amp  amp  dt1 date getTime    gt  dt2 date getTime            return true      return false     function utiljs isEqual firstDate  secondDate  returnFirstDate  returnSecondDate        if   firstDate     secondDate          return false      var dt1           dt2           if   utiljs isValidDateObjectOrDateString firstDate  dt1      utiljs isValidDateObjectOrDateString secondDate  dt2           return false      if  returnFirstDate          returnFirstDate date   dt1 date      if  returnSecondDate          returnSecondDate date   dt2 date      dt1 date setHours 0  0  0  0       dt2 date setHours 0  0  0  0       if  dt1 date getTime  amp  amp  dt2 date getTime  amp  amp  dt1 date getTime      dt2 date getTime            return true      return false     function utiljs firstDateEarlierThanSecond firstDate  secondDate  returnFirstDate  returnSecondDate        if   firstDate     secondDate          return false      var dt1           dt2           if   utiljs isValidDateObjectOrDateString firstDate  dt1      utiljs isValidDateObjectOrDateString secondDate  dt2           return false      if  returnFirstDate          returnFirstDate date   dt1 date      if  returnSecondDate          returnSecondDate date   dt2 date      dt1 date setHours 0  0  0  0       dt2 date setHours 0  0  0  0       if  dt1 date getTime  amp  amp  dt2 date getTime  amp  amp  dt1 date getTime    lt  dt2 date getTime            return true      return false     copy the whole code into a file and include  hope this helps

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I just do a remake of RobG solution  var daysInMonth    31 28 31 30 31 30 31 31 30 31 30 31   var isLeap   new Date theYear 1 29  getDate      29   if  isLeap      daysInMonth 1    29    return theDay  lt   daysInMonth --theMonth

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I recommend to use moment js  Only providing date to moment will validate it  no need to pass the dateFormat   var date   moment  2016-10-19      And then date isValid   gives desired result   Se post HERE

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One simple way to validate a date string is to convert to a date object and test that  e g    x000D   x000D     Expect input as d m y x000D  function isValidDate s    x000D    var bits   s split       x000D    var d   new Date bits 2   bits 1  - 1  bits 0    x000D    return d  amp  amp   d getMonth     1     bits 1   x000D    x000D   x000D    0 10 2017   29 2 2016   01 02   forEach function s    x000D    console log s           isValidDate s   x000D     x000D   x000D   x000D    When testing a Date this way  only the month needs to be tested since if the date is out of range  the month will change  Same if the month is out of range  Any year is valid   You can also test the bits of the date string    x000D   x000D  function isValidDate2 s    x000D    var bits   s split       x000D    var y   bits 2   x000D      m   bits 1   x000D      d   bits 0   x000D       Assume not leap year by default  note zero index for Jan  x000D    var daysInMonth    31  28  31  30  31  30  31  31  30  31  30  31   x000D   x000D       If evenly divisible by 4 and not evenly divisible by 100  x000D       or is evenly divisible by 400  then a leap year x000D    if     y   4   amp  amp  y   100       y   400     x000D      daysInMonth 1    29  x000D      x000D    return     D  test String d     amp  amp  d  gt  0  amp  amp  d  lt   daysInMonth --m  x000D    x000D   x000D    0 10 2017   29 2 2016   01 02   forEach function s    x000D    console log s           isValidDate2 s   x000D     x000D   x000D   x000D

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It s unfortunate that it seems JavaScript has no simple way to validate a date string to these days  This is the simplest way I can think of to parse dates in the format  m d yyyy  in modern browsers  that s why it doesn t specify the radix to parseInt  since it should be 10 since ES5     x000D   x000D  const dateValidationRegex      d 1 2    d 1 2    d 4     x000D  function isValidDate strDate    x000D    if   dateValidationRegex test strDate   return false  x000D    const  m  d  y    strDate split      map n   gt  parseInt n    x000D    return m     new Date y  m - 1  d  getMonth     1  x000D    x000D   x000D    10 30 2000abc    10 30 2000    1 1 1900    02 30 2000    1 1 1 4   forEach d   gt    x000D    console log d  isValidDate d    x000D      x000D   x000D   x000D

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This is ES6  with let declaration     function checkExistingDate year  month  day      year  month and day should be numbers         months are intended from 1 to 12     let months31    1 3 5 7 8 10 12      months with 31 days     let months30    4 6 9 11      months with 30 days     let months28    2      the only month with 28 days  29 if year isLeap       let isLeap     year   4     0   amp  amp   year   100     0       year   400     0        let valid    months31 indexOf month    -1  amp  amp  day  lt   31      months30 indexOf month    -1  amp  amp  day  lt   30      months28 indexOf month    -1  amp  amp  day  lt   28      months28 indexOf month    -1  amp  amp  day  lt   29  amp  amp  isLeap        return valid     it returns true or false     In this case I ve intended months from 1 to 12  If you prefer or use the 0-11 based model  you can just change the arrays with   let months31    0 2 4 6 7 9 11   let months30    3 5 8 10   let months28    1     If your date is in form dd mm yyyy than you can take off day  month and year function parameters  and do this to retrieve them   let arrayWithDayMonthYear   myDateInString split       let year   parseInt arrayWithDayMonthYear 2    let month    parseInt arrayWithDayMonthYear 1    let day   parseInt arrayWithDayMonthYear 0

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This solution does not address obvious date validations such as making sure date parts are integers or that date parts comply with obvious validation checks such as the day being greater than 0 and less than 32  This solution assumes that you already have all three date parts  year  month  day  and that each already passes obvious validations  Given these assumptions this method should work for simply checking if the date exists   For example February 29  2009 is not a real date but February 29  2008 is  When you create a new Date object such as February 29  2009 look what happens  Remember that months start at zero in JavaScript    console log new Date 2009  1  29      The above line outputs  Sun Mar 01 2009 00 00 00 GMT-0800  PST   Notice how the date simply gets rolled to the first day of the next month  Assuming you have the other  obvious validations in place  this information can be used to determine if a date is real with the following function  This function allows for non-zero based months for a more convenient input    var isActualDate   function  month  day  year        var tempDate   new Date year  --month  day       return month     tempDate getMonth         This isn t a complete solution and doesn t take i18n into account but it could be made more robust

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Does first function isValidDate s  proposed by RobG will work for input string  1 2    I think NOT  because the YEAR is not validated     My proposition is to use improved version of this function     input in ISO format  yyyy-MM-dd function DatePicker IsValidDate input            var bits   input split  -            var d   new Date bits 0   bits 1  - 1  bits 2            return d getFullYear      bits 0   amp  amp   d getMonth     1     bits 1   amp  amp  d getDate      Number bits 2

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var isDate    function input            var status   false          if   input    input length  lt   0              status   false            else             var result   new Date input             if  result     Invalid Date                 status   false              else               status   true                                return status            this function returns bool value of whether the input given is a valid date or not  ex    if isDate  var date          statements if the date is valid   else        statements if not valid

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function isValidDate year  month  day            var d   new Date year  month - 1  day  0  0  0  0           return   isNaN d   amp  amp   d getDate      day  amp  amp  d getMonth     1    month  amp  amp  d getYear      year

[javascript] How to validate a date?

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