Check if a JavaScript string is a URL

Question

Is there a way in JavaScript to check if a string is a URL?

RegExes are excluded because the URL is most likely written like stackoverflow; that is to say that it might not have a .com, www or http.

Answer 1

A related question with an answer:

Javascript regex URL matching

Or this Regexp from Devshed:

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 locator
  return !!pattern.test(str);
}