JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://rangy.googlecode.com/svn/trunk/currentrelease/rangy-core.js"></script>
<div id="contenteditable" contenteditable="true">
text text text text <b>bold bold bold</b> text text text
</div>

CSS

#contenteditable { border:1px solid red; padding:5px }

JavaScript

$(document).ready(function(){
  $('#contenteditable').bind('keyup', function(e){
    if (e.which == 88) {
      $('#contenteditable').find('b').contents().unwrap();
    }
  });
});