JSFiddle - React, Tailwind, and code Playground

HTML

<audio id="file1" src="http://www.freesound.org/data/previews/335/335253_3162775-lq.mp3" controls preload="auto"></audio>
<hr>
<audio id="file2" src="http://www.freesound.org/data/previews/331/331122_4490625-lq.mp3" controls preload="auto"></audio>

JavaScript

var file1 = document.querySelector('#file1');
var file2 = document.querySelector('#file2');

file1.onended = function() {file2.play();}
file2.onended = function() {file1.play();}

file1.play();