Question

72

How to check if a string is a legal dd/mm/yyyy date?

rated 0 times [ 77] [ 5] / answers: 1 / hits: 23223 / 13 Years ago, wed, september 28, 2011, 12:00:00

Given a string str, how could I check if it is in the dd/mm/yyyy format and contains a legal date ?

Some examples:

bla bla      // false

14/09/2011   //         true

09/14/2011   // false

14/9/2011    // false

1/09/2011    // false

14/09/11     // false

14.09.2011   // false

14/00/2011   // false

29/02/2011   // false

14/09/9999   //         true

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turnerf

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answered 13 Years ago aleenamarinr · Accepted Answer

Edit: exact solution below

You could do something like this, but with a more accurate algorithm for day validation:

function testDate(str) {

  var t = str.match(/^(d{2})/(d{2})/(d{4})$/);

  if(t === null)

    return false;

  var d = +t[1], m = +t[2], y = +t[3];



  // Below should be a more acurate algorithm

  if(m >= 1 && m <= 12 && d >= 1 && d <= 31) {

    return true;  

  }



  return false;

}

http://jsfiddle.net/aMWtj/

Date validation alg.: http://www.eee.hiflyers.co.uk/ProgPrac/DateValidation-algorithm.pdf

Exact solution: function that returns a parsed date or null, depending exactly on your requirements.

function parseDate(str) {

  var t = str.match(/^(d{2})/(d{2})/(d{4})$/);

  if(t !== null){

    var d = +t[1], m = +t[2], y = +t[3];

    var date = new Date(y, m - 1, d);

    if(date.getFullYear() === y && date.getMonth() === m - 1) {

      return date;   

    }

  }



  return null;

}

http://jsfiddle.net/aMWtj/2/

In case you need the function to return true/false and for a yyyy/mm/dd format

function IsValidDate(pText) {

    var isValid = false ;

    var t = pText.match(/^(d{4})/(d{2})/(d{2})$/);



    if (t !== null) {

        var y = +t[1], m = +t[2], d = +t[3];

        var date = new Date(y, m - 1, d);



        isValid = (date.getFullYear() === y && date.getMonth() === m - 1) ;

    }



    return isValid ;

}