<script>
function auto_completar(evento, valida, maiuscula) {
if (evento.target) {
codigo = evento.target;
}
else {
codigo = event.srcElement;
}
element = codigo.value;
if (maiuscula == 'true') {
element = element.toUpperCase();
}
var new_element = "";
for (vIdx=0; vIdx < element.length; vIdx++) {
if (valida.indexOf(element.substr(vIdx, 1)) != -1
|| (maiuscula == 'false' &&
valida.toLowerCase().indexOf(element.substr(vIdx, 1)) != -1) ) {
new_element = new_element + element.substr(vIdx, 1);
}
}
codigo.value = new_element;
var AC = new dmsAutoComplete('auto_complete','acDiv');
}
</script>
<input type="text" name="texto" size="20" onkeyup="auto_completar(event, ' ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'true');"> funcionou