Upper Case

Hello Everyone.

i have a question. i need to turn the text of two fields in upper case when i update the field.

i have this code but its not working, or if someone have a diferent code to turn  the text of string field to Upper Case appreciate.

function UpperCase(){
    var FIELDS_TO_UPDATE = ["Nome", "Descrição"]; //Update the field values to your field names
    function onLoad() {
    setToUpperCase(FIELDS_TO_UPDATE);
    }
    function setToUpperCase(fields) {
    for (var i in fields) {
        var str = Xrm.Page.getAttribute(fields[i]).getValue();
        var Upper = str.toUpperCase();
        Xrm.Page.getAttribute(fields[i]).setValue(Upper);
    }
    }
}