Jquery Autocomplete: the value passed to the ajax call is wrong

I have a reusable function of jquery Autocomplete in a file function.js. The function has as parameters the url for the ajax call and some additional values ​​taken from the fields of a form In another file, anag.js, I have several calls to this function.

The problem is that when it is executed, the value of the form fields remain the old one.

For example:

field prov = LI   
field city = Livorno  

When I change the value of the prov in MO, the function call autocomplete continues to have the value if field prov = LI.

I think it's a problem of binding function but can not figure out where is the error.

Autocomplete function (function.js)

function ajaxAutocomplete(elemId, dMinlength, dUrl, extraData){
    $("#" + elemId).autocomplete({
        source: function( request, response ) {
            $.ajax({
                url: dUrl,
                dataType: "json",
                data: 'term=' + request.term + '&' + extraData,
                success: function(data) {
                    response($.map(data, function(item) {
                        return { label: item.res };
                    }));
                }
            });
        },
        minLength: dMinlength
    });
};

Call to autocomplete function (anag.js)

$(function() {
    ajaxAutocomplete('luogo_nascita', 2, getBaseURL() + "/default/city_selector", 'prov=' + $("#prov").val() );
});

Thanks

Copyright Notice：Content Author:「volly86」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/23309105/jquery-autocomplete-the-value-passed-to-the-ajax-call-is-wrong