document.onkeyup ported to jQuery
<p>I'm porting some old Javascript to jQuery:</p>

<pre><code>document.onkeyup = function (event) {
    if (!event) window.event;
    ...
}
</code></pre>

<p>this code works on all major browsers. My jQuery code looks like:</p>

<pre><code>$(document).keyup = function (event) {
    ...
}
</code></pre>

<p>however this code is not working (the function is never triggered at least in IE7/8). Why? How to fix? </p>
