What's the recommended way of using something like this or prism.js to highlight a simple textarea containing code? I'm not talking a full-on programming edito

What's the recommended way of using something like this or prism.js to highlight a simple textarea containing code? I'm not talking a full-on programming editor, that's a much larger scope. Rather, I have an admin tool with a <textarea> that allows entering short code snippets, and it would be handy to see highlighting as you type. Even at this low level of complexity, is it simpler to just embed something like Ace, or is there an easy way to use a highlighting library?