Sunday, February 12, 2012

How do I determine if a string is date format?

I have some strings like this: 2012-02-05T07:42:47.000Z mixed with other strings. It is always in this format. (but the numbers are not the same, of course...the times are different) (not Sun, 05 Feb 2012 07:42:47 GMT )

I want to know whether a string matches that format. How can I determine that? It's so complicated with the colons and dots and stuff.


  1. Regex [0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}\.[0-9]{3}Z

  2. Isn't there are way to parse it directly into Java without a regex?
    With a regex you know IF it is a date but if you need also the value I should check on some date parser function.

  3. The ones for which !isNaN(+new Date(s))?

  4. Try matching with the following regular expression:

    var pattern = /\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}.\d{3}Z/;
    var d = "2012-02-05T07:42:47.000Z";
    if(d.match(pattern) !== null){
    } else {

  5. You can use Date.parse( your_string ) and check the result. This will check any allowed date format, unlike regex.
    Just realized your string is always in a given format, still unlike regex that function will check if day/month/year are correct etc. So maybe carry 2 checks: 1st to check string format, 2nd to check if numbers are right.