JSFiddle - React, Tailwind, and code Playground

by David Thomas

HTML

<label for="newOptionInput">New option</label>
<input id="newOptionInput" />
<button>add option</button>

<select id="combobox">
    <option value="apples">apples</option>
</select>

CSS

button {
    display: block;
}

JavaScript

$('button').click(
    function() {
        var newOption = $('#newOptionInput').val(),
            opts = [];
        $('#combobox option').each(
            function() {
                opts.push($(this).text());
            });
        
        if ($.inArray(newOption, opts) == -1) {
            $('<option />')
                .val(newOption)
                .text(newOption)
                .appendTo('#combobox');
        }
    });