[Victor D]

Originally Posted by Warwick

Well if it is a valuable url i.e. something.something.tld

So something like "domain.tld" or "domain.domain.tld/smth.php" is considering to be an invalid URL and no matter if 'http://' is present?
Try something like this:

var value = product_option_value("url");
if (value == false ) {
    alert("Sorry, you should enter an url");
    return false;
} 
var re =  new RegExp(/^(http:\/\/)?[^\.]+\.[^\.]+\.[^\.]+$/i);
if (! re.test(value)) {
    alert("Url you provided seems to be incorrect");
   return false;
}