Check if a string is a date value

Question

What is an easy way to check if a value is a valid date  any known date format allowed    For example I have the values 10-11-2009  10 11 2009  2009-11-10T07 00 00 0000 which should all be recognized as date values  and the values 200  10  350  which should not be recognized as a date value  What is the simplest way to check this  if this is even possible  Because timestamps would also be allowed

User · Answer

is it fine to check for a Date related function is available for the object to find whether it is a Date object or not ?

like

var l = new Date();
var isDate = (l.getDate !== undefined) ? true; false;

User · Answer

None of the answers here address checking whether the date is invalid such as February 31  This function addresses that by checking if the returned month is equivalent to the original month and making sure a valid year was presented     expected input dd mm yyyy or dd mm yyyy or dd-mm-yyyy function isValidDate s      var separators              -             var bits   s split new RegExp separators join        g       var d   new Date bits 2   bits 1  - 1  bits 0      return d getFullYear      bits 2   amp  amp  d getMonth     1    bits 1

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I would do this  var myDateStr  new Date  2015 5 2     if    isNaN   myDateStr getMonth            console log  Valid date      else       console log  Invalid date        Play here

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x000D   x000D  document getElementById  r1   innerHTML   dayjs  sdsdsd   isValid   x000D   x000D  document getElementById  r2   innerHTML   dayjs  2 6 20   isValid   x000D   lt script src  https   unpkg com dayjs 1 8 21 dayjs min js  gt  lt  script gt  x000D   x000D   lt p gt  sdsdsd  is a date   lt span id  r1  gt  lt  span gt  lt  p gt  x000D   lt p gt  2 6 20  is a date   lt span id  r2  gt  lt  span gt  lt  p gt  x000D   x000D   x000D    A light weight library is ready for you  Day js

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This is how I solved this problem in an app I m working on right now   updated based on feedback from krillgar   var isDate   function date        return  new Date date       Invalid Date    amp  amp   isNaN new Date date

User · Answer

Use Regular expression to validate it    isDate  2018-08-01T18 30 00 000Z     isDate  date           const  regExp    new RegExp    -     1-9  0-9     0-9  4  - 1 0-2  0 1-9  - 3 01  0 1-9   12  0-9  T 2 0-3   01  0-9     0-5  0-9     0-5  0-9     0-9     Z               return  regExp test  date

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By referring to all of the above comments  I have come to a solution   This works if the Date passed is in ISO format or need to manipulate for other formats    var isISO    2018-08-01T18 30 00 000Z    if  new Date isISO       Invalid Date   amp  amp   isNaN new Date isISO          if isISO    new Date isISO  toISOString              console log  Valid date          else           console log  Invalid date            else       console log  Invalid date        You can play here on JSFiddle

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Would Date parse   suffice   See its relative MDN Documentation page

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function isDate dateStr      return  isNaN new Date dateStr  getDate         This will work on any browser since it does not rely on  quot Invalid Date quot  check  This will work with legacy code before ES6  This will work without any library  This will work regardless of any date format  This does not rely on Date parse which fails the purpose when values like  quot Spiderman 22 quot  are in date string  This does not ask us to write any RegEx

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Ok  this is an old question  but I found another solution while checking the solutions here  For me works to check if the function getTime   is present at the date object   const checkDate   new Date dateString    if  typeof checkDate getTime      function       return

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This is how I end up doing it  This will not cover all formats  You have to adjust accordingly  I have control on the format  so it works for me  function isValidDate s                var dt                   var bits                   if  s  amp  amp  s length  gt   6                    if  s indexOf       gt  -1                        bits   s split                                         else if  s indexOf  -    gt  -1                        bits   s split  -                                      else if  s indexOf       gt  -1                        bits   s split                                         try                       dt   new Date bits 2   bits 0  - 1  bits 1                      catch  e                        return false                                    return  dt getMonth     1      parseInt bits 0                  else                   return false

User · Answer

This callable function works perfectly  returns true for valid date  Be sure to call using a date on ISO format  yyyy-mm-dd or yyyy mm dd    function validateDate isoDate         if  isNaN Date parse isoDate              return false        else           if  isoDate     new Date isoDate   toISOString   substr 0 10                 return false                      return true

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Here is an improved function that uses only Date parse     function isDate s        if isNaN s   amp  amp   isNaN Date parse s            return true      else return false      Note  Date parse   will parse numbers  for example Date parse 1  will return a date  So here we check if s is not a number the  if it is a date

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I know it s an old question but I faced the same problem and saw that none of the answers worked properly - specifically weeding out numbers  1 200 345 etc    from dates  which is the original question  Here is a rather unorthodox method I could think of and it seems to work  Please point out if there are cases where it will fail   if sDate toString      parseInt sDate  toString    return false    This is the line to weed out numbers  Thus  the entire function could look like    x000D   x000D  function isDate sDate      x000D    if sDate toString      parseInt sDate  toString    return false   x000D    var tryDate   new Date sDate   x000D    return  tryDate  amp  amp  tryDate toString       NaN   amp  amp  tryDate     Invalid Date      x000D    x000D   x000D  console log  100   isDate 100    x000D  console log  234   isDate  234     x000D  console log  hello   isDate  hello     x000D  console log  25 Feb 2018   isDate  25 Feb 2018     x000D  console log  2009-11-10T07 00 00 0000   isDate  2009-11-10T07 00 00 0000     x000D   x000D   x000D

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How about something like this  It will test if it is a Date object or a date string   function isDate value        var dateFormat      if  toString call value        object Date              return true            if  typeof value replace      function             value replace    s   s   gm                 dateFormat       d 1 4         -  d 1 2         -  d 1 4    s    0  1-9   0-5  1    012   d  0-5   d s  ap m          return dateFormat test value       I should mention that this doesn t test for ISO formatted strings but with a little more work to the RegExp you should be good

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SimpleDateFormat sdf   new SimpleDateFormat dateFromat   sdf setLenient false     By default this is set to TRUE  So even strings of wrong format return good values   I have used it something like this    SimpleDateFormat formatter   new SimpleDateFormat  yyyy MM dd    formatter setLenient false   String value    1990 13 23     try         Date date   formatter parse value         System out println date        catch  ParseException e           System out println  its bad

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new Date date       Invalid Date  only works in Firefox and Chrome  IE8  the one I have on my machine for testing purposes  gives NaN   As was stated to the accepted answer  Date parse date  will also work for numbers  So to get around that  you could also check that it is not a number  if that s something you want to confirm    var parsedDate   Date parse date       You want to check again for  isNaN parsedDate  here because Dates can be converted    to numbers  but a failed Date parse will not  if  isNaN date   amp  amp   isNaN parsedDate            do your work

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2015 Update  It is an old question but other new questions like    How to validate if a string is a valid date in js   get closed as duplicates of this one  so I think it s important to add some fresh info here  I m writing it because I got scared thinking that people actually copy and paste some of the code posted here and use it in production   Most of the answers here either use some complex regular expressions that match only some very specific formats and actually do it incorrectly  like matching January 32nd while not matching actual ISO date as advertised - see demo  or they try to pass anything to the Date constructor and wish for the best   Using Moment  As I explained in this answer there is currently a library available for that  Moment js  It is a library to parse  validate  manipulate  and display dates in JavaScript  that has a much richer API than the standard JavaScript date handling functions   It is 12kB minified gzipped and works in Node js and other places   bower install moment --save   bower npm install moment --save     npm Install-Package Moment js     NuGet spm install moment --save     spm meteor add momentjs moment    meteor   Using Moment you can be very specific about checking valid dates  Sometimes it is very important to add some clues about the format that you expect  For example  a date such as 06 22 2015 looks like a valid date  unless you use a format DD MM YYYY in which case this date should be rejected as invalid  There are few ways how you can tell Moment what format you expect  for example   moment  06 22 2015    MM DD YYYY   true  isValid       true moment  06 22 2015    DD MM YYYY   true  isValid       false   The true argument is there so the Moment won t try to parse the input if it doesn t exactly conform to one of the formats provided  it should be a default behavior in my opinion    You can use an internally provided format   moment  2015-06-22T13 17 21 0000   moment ISO 8601  true  isValid       true   And you can use multiple formats as an array   var formats         moment ISO 8601       MM DD YYYY      HH mm ss     moment  2015-06-22T13 17 21 0000   formats  true  isValid       true moment  06 22 2015      13 17 21   formats  true  isValid       true moment  06 22 2015      13 17 21   formats  true  isValid       false   See  DEMO   Other libraries  If you don t want to use Moment js  there are also other libraries    XDate DateJS   2016 Update  I created the immoment module that is like  a subset of  Moment but without surprises caused by mutation of existing objects  see the docs for more info    2018 Update  Today I recommend using Luxon for date time manipulation instead of Moment  which  unlike Moment  makes all object immutable so there are no nasty surprises related to implicit mutation of dates   More info  See also    Managing Dates and Times Using Moment js by Jay Raj Working with JavaScript Dates Using Moment js by Bradley Holbrook   A series of articles by Rob Gravelle on JavaScript date parsing libraries    A Roundup of Popular JavaScript Date Parsing Libraries  Moment js A Roundup of Popular JavaScript Date Parsing Libraries  Datejs A Roundup of Popular JavaScript Date Parsing Libraries  XDate   Bottom line  Of course anyone can try to reinvent the wheel  write a regular expression  but please actually read ISO 8601 and RFC 3339 before you do it  or call buit-in constructors with random data to parse error messages like  Invalid Date   Are you sure this message is exactly the same on all platforms  In all locales  In the future   or you can use a tested solution and use your time to improve it  not reinvent it  All of the libraries listed here are open source  free software

User · Answer

Here s a minimalist version   var isDate   function  date        return   function d  return d    Invalid Date  amp  amp  isNaN d     new Date date

User · Answer

Try this   if  var date   new Date yourDateString            if you get here then you have a valid date

[javascript] Check if a string is a date value

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