#javascript

(1)

The JavaScript (jQuery):

<script>
$('form').submit(function(){    
        if ($('input#website').val().length != 0) {
            return false;
        } 
});
</script>

The HTML:

<form method="get" action="/">
<input name="firstname" type="text" value="First Name" />
<input name="lastname" type="text" value="Last Name" />
<input id="website" name="website" type="text" value=""  />
<input type="submit" value="Submit" />
</form>