JqueryUI autocomplete con JSON

Código html:


<style>
.ui-autocomplete { height: 400px; overflow-y: scroll; overflow-x: hidden;}

</style>

<input id="id_mantis" type="text" size="6" style="" />

<script>
   $(document).ready(function() {
      CargarAutocompletar("nombre_del_campo_de_texto", 2);
   });
</script>

Código JS:

function CargarAutocompletar(id_input, modo)
{
$.ui.autocomplete.prototype._renderItem = function (ul, item) {
item.label = item.label.replace(new RegExp("(?![^&;]+;)(?!<[^<>]*)(" + $.ui.autocomplete.escapeRegex(this.term) + ")(?![^<>]*>)(?![^&;]+;)", "gi"), "<span style='font-weight:bold;color:Blue;'>$1</span>");
return $("<li></li>")
.data("item.autocomplete", item)
.append("<a>" + item.label + "</a>")
.appendTo(ul);
    };

jQuery.support.cors = true;
$.ajaxSetup({ cache: false });

var urlServicio = "http://" + window.self.location.hostname + "/wsX/Parametros.asmx/ObtenerChoiceListItemsJSON";

$("#" + id_input).autocomplete({
source: function( request, response ) {
$.ajax({
url: urlServicio,
dataType: "json",
data: {term: request.term,
  dcnFiltro: $("#" + id_input).val(),
  random: Math.floor(Math.random()*9999999999)},
success: function(data) {
response($.map(data, function(item) {
return {
label: item.dcn_cod,
id: item.dcn_dsc                                    
};
}));
}
});
},
minLength: 2,
select: function(event, ui) {
//quito tags html
var dcn = ui.item.label.replace(/<(?:.|\n)*?>/gm, '');
alert(dcn);                    
}
});
}