JSFiddle - React, Tailwind, and code Playground

HTML

<select name="lstClients" id="lstClients" class="Combobox lstSearchClients" >
  <option value="1">Client 1</option>
  <option value="2">Client 2</option>
</select>


<select name="lstOptions" id="lstOptions" class="Combobox lstSearchClients" style="display:none;">
  <option value="1">Option 1</option>
  <option value="2">Option 2</option>
</select>

JavaScript

(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
                        });
                        select.trigger("change");
                    },
                    change: function (event, ui) {
                        if (!ui.item) {
                            var matcher = new RegExp("^" + $.ui.autocomplete.escapeRegex($(this).val())...