How to check a dirty flag

I was wondering what the best way is to check if a page is dirty if the user chooses to navigate away from it. For example, there is a registration form and the user enters all their information. Then accidentally clicks on the link to navigate away from it.

I found this on the internet where it checks to see if the page is dirty if a person makes changes to any form input values.

<script type="text/javascript">
var isDirty = false;
var msg = 'You haven\'t saved your changes.';
$(document).ready(function(){
    $(':input').change(function(){
        if(!isDirty){
            isDirty = true;
        }
    });
    window.onbeforeunload = function(){
        if(isDirty){
            return msg;
        }
    };
});
</script>

      

        
        
        
      

    

So this works great. But how can I exclude some of the links that pop up? Is there a better way to do this?