define keycode (press from keyboard)

$(document).ready(function()
    {
        $(document).keydown(function (eventObj)
        {
            /* display the key and character code for the key you pressed */
            alert("Key pressed: "+getKey(eventObj)+ " Code = "+getKeyCode(eventObj));
        });
    });
    function getKeyCode(key)
    {
        //return the key code
        return (key == null) ? event.keyCode : key.keyCode;
    }

    /* get key character */
    function getKey(key)
    {
        //return the key
        return String.fromCharCode(getKeyCode(key)).toLowerCase();
    }