//first, tell the browsers to react to the event
if( document.captureEvents && Event.KEYUP ) {
    //remove this part if you do not need Netscape 4 to work
    document.captureEvents( Event.KEYUP );
}
/* this next line tells the browser to detect a keyup
event over the whole document and when it detects it,
it should run the event handler function 'alertkey' */
document.onkeyup = alertkey;

//now create the event handler function to process the event
function alertkey(e) {
    if( !e ) {
        //if the browser did not pass the event information to the
        //function, we will have to obtain it from the event register
        if( window.event ) {
            //Internet Explorer
            e = window.event;
        } else {
            //total failure, we have no way of referencing the event
            return;
        }
    }
    if( typeof( e.keyCode ) == 'number'  ) {
        //DOM
        e = e.keyCode;
    } else if( typeof( e.which ) == 'number' ) {
        //NS 4 compatible
        e = e.which;
    } else if( typeof( e.charCode ) == 'number'  ) {
        //also NS 6+, Mozilla 0.9+
        e = e.charCode;
    } else {
        //total failure, we have no way of obtaining the key code
        return;
    }
    
    if (e == 13) {
        document.getElementById("cmdSubmit").click();
    }
}