JSFiddle - React, Tailwind, and code Playground

HTML

<select id="dropdown">
    <option value="1">First</option>
    <option value="2">Second</option>
</select>

JavaScript

$('body').keypress(function (event) {
    var key = String.fromCharCode(event.which);
    if (key == 'a') {
        var e = document.createEvent("MouseEvents");
        e.initMouseEvent("mousedown", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
        $("#dropdown").get(0).dispatchEvent(e);
    }
});