JSFiddle - React, Tailwind, and code Playground

HTML

<audio id="audio_player"></audio>
<textarea id="sentence" cols="25" rows="5"></textarea>
<br>
<button id="play_button">Play</button>
<br>
<input type="checkbox" id="connacht" checked>Connacht
<br>
<input type="checkbox" id="munster">Munster
<br>
<input type="checkbox" id="ulster">Ulster
<br>
<label id="playing"></label>

JavaScript

var _playlist = [];
    var _wordlist = [];

    var _player = document.getElementById("audio_player");
    var _playlist_index = 0;

    var _sentence = document.getElementById("sentence");

    var _connacht = document.getElementById("connacht");
    var _munster = document.getElementById("munster");
    var _ulster = document.getElementById("ulster");
    var _dialect = "Connacht";

    var _playing = document.getElementById("playing");

    var _play_button = document.getElementById("play_button");

    var _path_mpeg = "http://www.focloir.ie/media/ei/sounds/";
    var _path_ogg = "http://www.focloir.ie/media/ei/sounds_ogg/";

    var _max_phrase_size = 3;
    var _current_phrase_size = _max_phrase_size;

    function play() {
        _max_phrase_size = 3;
        _current_phrase_size = _max_phrase_size;

        _playlist = _sentence.value;
        _playlist = _playlist.replace(/\!/g, " ");
        _playlist = _playlist.replace(/\?/g, " ");
        _playlist = _playlist.replace(/\./g, " ");
        _playlist = _playlist.replace(/,/g, " ");
        _playlist = _playlist.replace(/\r/g, " ");
        _playlist = _playlist.replace(/\n/g, " ");
        _playlist = _playlist.replace(/ +(?= )/g, '');
        _playlist = _playlist.trim();

        _wordlist = _playlist.split(" ");

        _playlist = _playlist.toLowerCase();
        _playlist = _playlist.replace(/á/g, "a_x");
        _playlist = _playlist.replace(/é/g, "e_x");
        _playlist = _playlist.replace(/í/g, "i_x");
        _playlist = _playlist.replace(/ó/g, "o_x");
        _playlist = _playlist.replace(/ú/g, "u_x");

        _playlist = _playlist.split(" ");

        _playlist_index = 0;
        _play_button.disabled = true;
        next();
    }

    function next() {
        if (_playlist_index < _playlist.length) {

            if (_dialect == "Connacht") dialect = "c";
            else if (_dialect == "Munster") dialect = "m";
            else dialect = "u";

            playing =...