[jQuery] onchange input

[jQuery] onchange input


I have:
<form method="post" action="/rejestracja"> <table>
<input type="text" name="sf_guard_user[username]"
id="sf_guard_user_username" /></td>
<input type="submit" name="register" value="Zarejestruj" />
</form>
<p id="information">
I would like after each change in input 'sf_guard_user_username' write
something between <p id="information"> .
What is wrong in my code below:
$(document).ready(function()
{
$('#sf_guard_user_username').onchange(function()
    {
     $("#information").html("ddddd");
});
});
??