JqueryUi autocomplete Combobox change is not working

I have implemented the jquery autocomplete combobox, however the change event does not seem to be working. The value of the underlying select element does not change. I put a breakpoint in firebug for the change event of the combobox but the condition in the change if (!ui.item) is always false. The value of ui.item is Object { label="560011-Jayangar III Block", value="560011-Jayangar III Block", option=option}

Shouldn't the condition be if (ui.item)? I am a bit confused.

(function($) {
            $.widget("ui.combobox", {
                _create: function() {
                    var self = this,
                    select = this.element.hide(),
                    selected = select.children(":selected"),
                    value = selected.val() ? selected.text() : "";
                    var input = this.input = $("<input>")
                    .insertAfter(select)
                    .val(value)
                    .autocomplete({
                        delay: 0,
                        minLength: 0,
                        source: function(request, response) {
                            var matcher = new RegExp($.ui.autocomplete.escapeRegex(request.term), "i");
                            response(select.children("option").map(function() {
                                var text = $(this).text();
                                if (this.value && (!request.term || matcher.test(text)))
                                    return {
                                        label: text.replace(
                                            new RegExp(
                                                "(?![^&;]+;)(?!<[^<>]*)(" +
                                                $.ui.autocomplete.escapeRegex(request.term) +
                                                ")(?![^<>]*>)(?![^&;]+;)", "gi"
                                            ), "<strong>$1</strong>"),
                                        value: text,
                                        option: this
                                    };
                            }));
                        },
                        select: function(event, ui) {
                            ui.item.option.selected = true;
                            self._trigger("selected", event, {
                                item: ui.item.option
                            });
                        },
                        change: function(event, ui) {
                            if (!ui.item) {
                                var matcher = new RegExp("^" + $.ui.autocomplete.escapeRegex($(this).val()) + "$", "i"),
                                    valid = false;
                                select.children("option").each(function() {
                                    if ($(this).text().match(matcher)) {
                                        this.selected = valid = true;
                                        return false;
                                    }
                                });
                                if (!valid) {
                                    // remove invalid value, as it didn't match anything
                                    $(this).val("");
                                    select.val("");
                                    input.data("autocomplete").term = "";
                                    return false;
                                }
                            }
                        }
                    })
                    .addClass("ui-widget ui-widget-content ui-corner-left");

                    input.data("autocomplete")._renderItem = function(ul, item) {
                        return $("<li></li>")
                        .data("item.autocomplete", item)
                        .append("<a>" + item.label + "</a>")
                        .appendTo(ul);
                    };

                    this.button = $("<button type='button'>&nbsp;</button>")
                    .attr("tabIndex", -1)
                    .attr("title", "Show All Items")
                    .insertAfter(input)
                    .button({
                        icons: {
                            primary: "ui-icon-triangle-1-s"
                        },
                        text: false
                    })
                    .removeClass("ui-corner-all")
                    .addClass("ui-corner-right ui-button-icon")
                    .click(function() {
                        // close if already visible
                        if (input.autocomplete("widget").is(":visible")) {
                            input.autocomplete("close");
                            return;
                        }

                        // work around a bug (likely same cause as #5265)
                        $(this).blur();

                        // pass empty string as value to search for, displaying all results
                    开发者_运维知识库    input.autocomplete("search", "");
                        input.focus();
                    });
                },

                destroy: function() {
                    this.input.remove();
                    this.button.remove();
                    this.element.show();
                    $.Widget.prototype.destroy.call(this);
                }
            });
        })(jQuery);

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The combobox was working fine. There was some other jquery code which was resetting things on change. Things are working as expected now.