JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://underscorejs.org/underscore-min.js"></script>
<link rel="stylesheet" href="http://twitter.github.com/bootstrap/assets/css/bootstrap.css">
<link rel="stylesheet" href="http://twitter.github.com/bootstrap/assets/css/bootstrap-responsive.css">
<div class="container-fluid">
    <div class="row-fluid">
        <!-- MARKUP GOES HERE -->
        <textarea id="type"></textarea>
        <textarea id="output"></textarea>
        <!-- END MARKUP -->
    </div>
</div>

<!-- http://html-ipsum.com/ for sample markup -->

CSS

body { margin-top: 20px; }

JavaScript

$('#type').on('keyup',function(){
    $('#output').text($(this).val());
});