Converter minúsculo em maisculo no Chrome

// IE
if (window.event) {
    keynum = event.keyCode;
}
// Netscape/Firefox/Opera
else if (event.which) {
    keynum = event.which;
}

if ((keynum >= 97 && keynum <= 122) || (keynum >= 224 && keynum <= 255)) {
    // converte de acordo com o valor decimal da tecla na tabela ascii    
    keynum = keynum - 32;
    
    // IE
    if (window.event) {
        window.event.keyCode = keynum;
    }
    // firefox e outros que usam o Gecko
    else if (event.which) {
        var newEvent = document.createEvent("KeyEvents");
        newEvent.initKeyEvent("keypress", true, true, document.defaultView,
                    event.ctrlKey, event.altKey, event.shiftKey,
                    event.metaKey, 0, keynum);
        event.preventDefault();
        event.target.dispatchEvent(newEvent);
    }
}

return true;