unobstrusive
HTML
<h1>Here's the password</h1>
<input type="password" name="pwpw" id="pwpw"/>
<span name="status">aa</span>
JavaScript
$(document).ready(function(e) {
function CreateUser() {
if ( document.getElementsByName("pwpw").value != "" )
document.getElementsByName("status").innerHTML = "SUX!";
}
$('#pwpw').on('keyup', CreateUser);
});