How to get selected value of an autopopulate text input

Hi all,

I was able to auto populate a string field in order to get right suggestions using addOnkeyPress,
I need to get the selected value so I call the changeAutocomplete() during the OnChange field event

but in the alert, I get just what the user wrote in the field and not the complete resultSet value of my autocomplete array values.

I need "Matteo" in the alert and not only "m".

var keyPressFcn = function (ext) {

try {

var userInput = Xrm.Page.getControl("tclab_casepriority").getValue();
resultSet = {
results: new Array(),
commands: null
};

var userInputLowerCase = userInput.toLowerCase();

for (i = 0; i < persona.length; i++) {

if (userInputLowerCase === persona[i].name.substring(0, userInputLowerCase.length).toLowerCase()) {
resultSet.results.push({
id: i,
fields: [persona[i].name,persona[i].code
]});
}

}

if (resultSet.results.length > 0) {

ext.getEventSource().showAutoComplete(resultSet);

}

else {

ext.getEventSource().hideAutoComplete();

}}

catch (e) {

console.log(e);
}};

var a = Xrm.Page.getControl("tclab_casepriority");

if (a!=null) {

a.addOnKeyPress(keyPressFcn)

}}
function changeAutocomplete() {

var b = Xrm.Page.getAttribute("tclab_casepriority").getValue();

//This is happening also using getControl method

// var b = Xrm.Page.getControl("tclab_casepriority").getValue();

alert(b);

}

At The end I will need also to do the same thing with the Case Severity field, filtering auto-populate suggestions based on the CasePriority autocomplete field. I think when I will get the right value I would replicate the autocomplete also for the case severity field.

THANK YOU IN ADVANCE FOR YOUR SUGGESTIONS