JSFiddle - React, Tailwind, and code Playground
HTML
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/ui-lightness/jquery-ui.css">
<div id='container'>
some text
<span>some more text</span>
and more text
</div>
JavaScript
var element = document.getElementById('container');
var text = element.innerText || element.textContent;
alert( text );