JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://facebook.github.io/react/js/showdown.js"></script>
<html>
<body>
</body>
</html>

CoffeeScript

{div, h3, textarea} = React.DOM
converter = new Showdown.converter()

MarkdownEditor = React.createClass
  getInitialState: ->
    value: 'Type some *markdown* here!'

  handleKeyUp: React.autoBind ->
    @setState value: @refs.textarea.getDOMNode().value

  render: ->
    (div {className: 'MarkdownEditor'}, [
      (h3 {}, ['Input']),
      (textarea {onKeyUp: @handleKeyUp, ref: 'textarea'}, 
        @state.value
      ),
      (h3 {}, ['Output']),
      (div {
        className: 'content'
        dangerouslySetInnerHTML:
          __html: converter.makeHtml @state.value
      })
    ])

React.renderComponent (MarkdownEditor {}), document.body