url validation using javascript

Question

Hi,

I want to validate url and want to display message. Below is my code.

$("#pageUrl").keydown(function(){
     $(".status").show();
     var url = $("#pageUrl").val();

     if(isValidURL(url)){

     $.ajax({
      type: "POST",
      url: "demo.php",
      data: "pageUrl="+ url,
      success: function(msg){
       if(msg == 1 ){
        $(".status").html('<img src="images/success.gif"/><span><strong>SiteID:</strong>12345678901234456</span>');
       }else{
        $(".status").html('<img src="images/failure.gif"/>');
       }
      }
      });

      }else{

        $(".status").html('<img src="images/failure.gif"/>');
      }

    });


function isValidURL(url){
    var RegExp = /(ftp|http|https):\/\/(\w+:{0,1}\w*@)?(\S+)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/]))?/;

    if(RegExp.test(url)){
        return true;
    }else{
        return false;
    }
}

My problem is now it will show error message even he is entering proper url until it matches regular expression, and it return true even if url is something like "http://wwww".

I appreciate your suggestions.

Answer 1

If you're looking for a more reliable regex, check out RegexLib. Here's the page you'd probably be interested in:

http://regexlib.com/Search.aspx?k=url

As for the error messages showing while the person is still typing, change the event from keydown to blur and then it will only check once the person moves to the next element.

Answer 2

It's not practical to parse URLs using regex. A full implementation of the RFC1738 rules would result in an enormously long regex (assuming it's even possible). Certainly your current expression fails many valid URLs, and passes invalid ones.

Instead:

a. use a proper URL parser that actually follows the real rules. (I don't know of one for JavaScript; it would probably be overkill. You could do it on the server side though). Or,

b. just trim away any leading or trailing spaces, then check it has one of your preferred schemes on the front (typically ‘http://’ or ‘https://’), and leave it at that. Or,

c. attempt to use the URL and see what lies at the end, for example by sending it am HTTP HEAD request from the server-side. If you get a 404 or connection error, it's probably wrong.

it return true even if url is something like "http://wwww".

Well, that is indeed a perfectly valid URL.

If you want to check whether a hostname such as ‘wwww’ actually exists, you have no choice but to look it up in the DNS. Again, this would be server-side code.

Answer 3

You can try this short code to validate a url in a form:

function checkURL(value) {
  var urlregex = new RegExp(
        "^(http:\/\/www.|https:\/\/www.|ftp:\/\/www.|www.){1}([0-9A-Za-z]+\.)");
  if(urlregex.test(value))
  {
    return(true);
  }
  return(false);
}

Answer 4

The Jquery plugin Validation validates URL too. http://docs.jquery.com/Plugins/Validation/Methods/url

Answer 5

hey try this

 function validateURL(textval) {
      var urlregex = new RegExp(
            "^(http|https|ftp)\://([a-zA-Z0-9\.\-]+(\:[a-zA-Z0-9\.&%\$\-]+)*@)*((25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])|([a-zA-Z0-9\-]+\.)*[a-zA-Z0-9\-]+\.(com|edu|gov|int|mil|net|org|biz|arpa|info|name|pro|aero|coop|museum|[a-zA-Z]{2}))(\:[0-9]+)*(/($|[a-zA-Z0-9\.\,\?\'\\\+&%\$#\=~_\-]+))*$");
      return urlregex.test(textval);
    }

this can return true for urls like http://stackoverflow.com/questions/1303872/url-validation-using-javascript or http://regexlib.com/DisplayPatterns.aspx?cattabindex=1&categoryId=2

thank you