Question

I am trying to use RegEX to match a URL pattern. I found an answer here:
Check if a Javascript string is a url

Which pointed me to here:
http://forums.devshed.com/javascript-development-115/regexp-to-match-url-pattern-493764.html

Which gave me the following code(cut and pasted from devshed to here and to my script):

function ValidURL(str) {
   var pattern = new RegExp('^(https?:\/\/)?'+ // protocol
      '((([a-z\d]([a-z\d-]*[a-z\d])*)\.)+[a-z]{2,}|'+ // domain name
      '((\d{1,3}\.){3}\d{1,3}))'+ // OR ip (v4) address
      '(\:\d+)?(\/[-a-z\d%_.~+]*)*'+ // port and path
      '(\?[;&a-z\d%_.~+=-]*)?'+ // query string
      '(\#[-a-z\d_]*)?$','i'); // fragment locater
   if(!pattern.test(str)) {
      alert("Please enter a valid URL.");
      return false;
   } else {
      return true;
   }
}

When I attempt to use it in Firefox 4.0, Firebug 1.7.3 gives me an invalid quantifier error at:

      '(\#[-a-z\d_]*)?$','i'); // fragment locater

Does anyone have an idea on what the issue might be?

From other searches on invalid quantifier, I believe that * is an issue but not sure what it might be. The string in question that I am using the function on when it gives me the error is:

htp://localhost:1987/

ADDED COMMENT
The fix suggested by agent-j at least removed the invalid quantifier issue. thumbs up

However, it doesn’t like the sample url above when done correctly:

    http://localhost:1987/

The issue is with the port. When I remove the port #, it likes localhost.

Answer 1

You need to escape the first \ in here:

'(\?[;&a-z\d%_.~+=-]*)?'

becomes

'(\\?[;&a-z\d%_.~+=-]*)?'