JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://robins.homeserver.com/home/jquerycourse/jquery-ui-1.8.9.custom.css">
<html>
    <head>
        <title>Testing Combobox</title>
    </head>
    <body>
        
        <!-- Biiig list of colours -->
        <select>
            <option>Air Force blue</option>
            <option>Alice blue</option>
            <option>Alizarin</option>
            <option>Almond</option>
            <option>Amaranth</option>
            <option>Amber</option>
            <option>Amber (SAE/ECE)</option>
            <option>American rose</option>
            <option>Amethyst</option>
            <option>Anti-flash white</option>
            <option>Antique brass</option>
            <option>Antique fuchsia</option>
            <option>Antique white</option>
            <option>Ao</option>
            <option>Ao (English)</option>
            <option>Apple green</option>
            <option>Apricot</option>
            <option>Aqua</option>
            <option>Aquamarine</option>
            <option>Army green</option>
            <option>Arsenic</option>
            <option>Arylide yellow</option>
            <option>Ash grey</option>
            <option>Asparagus</option>
            <option>Atomic tangerine</option>
            <option>Auburn</option>
            <option>Aureolin</option>
            <option>AuroMetalSaurus</option>
            <option>Awesome (color)</option>
            <option>Azure (color wheel)</option>
            <option>Azure (web) (Azure mist)</option>
            <option>Baby blue</option>
            <option>Baby blue eyes</option>
            <option>Baby pink</option>
            <option>Ball Blue</option>
            <option>Banana Mania</option>
            <option>banana yellow</option>
            <option>Battleship grey</option>
            <option>Bazaar</option>
            <option>Beau blue</option>
            <option>Beaver</option>
            <option>Beige</option>
            <option>Bisque</option>
 ...

CSS

.ui-button { margin-left: -1px; }
.ui-button-icon-only .ui-button-text { padding: 0.35em; } 
.ui-autocomplete-input { margin: 0; padding: 0.48em 0 0.47em 0.45em; }

JavaScript

//The jQuery UI AutoComplete Combobox script from the jQuery UI documentation:
//http://jqueryui.com/demos/autocomplete/#combobox
(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;
                               ...