jQuery also has an excellent implementation that's incredibly easy to use. Here's how you could implement this functionality across browsers:

$(document).keypress(function(e){

    var checkWebkitandIE=(e.which==26 ? 1 : 0);

    var checkMoz=(e.which==122 && e.ctrlKey ? 1 : 0);



    if (checkWebkitandIE || checkMoz) $(body).append(<p>ctrl+z detected!</p>);

});

Tested in IE7,Firefox 3.6.3 & Chrome 4.1.249.1064

Another way of doing this is to use the keydown event and track the event.keyCode. However, since jQuery normalizes keyCode and charCode using event.which, their spec recommends using event.which in a variety of situations:

$(document).keydown(function(e){

if (e.keyCode==90 && e.ctrlKey)

    $(body).append(<p>ctrl+z detected!</p>);

});