JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://raw.github.com/jnbdz/EncodeAndDecodeXML/master/Source/EncodeAndDecodeXML.js"></script>
<textarea id="content"></textarea><br/>
<button id="htmlencode">Encode</button><button id="htmldecode">Decode</button>
<br/>
<textarea id="result"></textarea>

JavaScript

document.id('htmlencode').addEvent('click', function(){
    var content = document.id('content');
    document.id('result').set('value', content.get('value').encodeXML());
});

document.id('htmldecode').addEvent('click', function(){
    var content = document.id('content');
    document.id('result').set('value', content.get('value').decodeXML());
});