URL validation jquery

URL validation jquery

HTML

<script src="https://getfirebug.com/firebug-lite-debug.js"></script>
<input type="text" name="extrnal_url" id="extrnal_url" value=""  />

CSS

.validated_ok{border:1px solid green}
.validated_error{border:1px solid red}

JavaScript

$('#extrnal_url').change(function() {
  alert('here');
   var website_name = 'www.justdial.com';
   var extrnal_url  = $('#extrnal_url').val();
   alert(extrnal_url);


 var web_check1 = extrnal_url.match(/^(([\w]+:)?\/\/)?(([\d\w]|%[a-fA-f\d]{2,2})+(:([\d\w]|%[a-fA-f\d]{2,2})+)?@)?([\d\w][-\d\w]{0,253}[\d\w]\.)+[\w]{2,15}(:[\d]+)?(\/([-+_~.\d\w]|%[a-fA-f\d]{2,2})*)*(\?(&?([-+_~.\d\w]|%[a-fA-f\d]{2,2})=?)*)?(#([-+_~.\d\w]|%[a-fA-f\d]{2,2})*)?$/g);


    if(web_check1 == null){
      alert('if');
      this.err_msg.push("Invalid Website address : "+website_name);
    }
    else
    {
      alert('else');
      var web_check2 = website_name.match(/w{4,}/g);
      if(web_check2!=null){
        alert('ifhdgcjdsgjd');
        console.log("Invalid Website address : "+website_name);
      }
      else if(extrnal_url=='justdial.com'){
        alert('elsejfdjsflsdk;f');
        console.log("External URL should not contain justdial.com. : "+website_name);
      }
    }
});