JQUERY to filter input in a textfield
<p>I am a newbie to jquery and javascript so this may be a silly question</p>

<p>I have a textfield and i would like to filter the input</p>

<p>so it will only let the usesr enter in [A-Z] chacters and also if the length of [A-Z] has reached 3 it then also disables the user from entereing any more characters</p>
