title: Implementing undo functionality in JavaScript
body: <p>How do I implement a ctrl z in javascript?</p>
  
  <p>After numerous google searches, I stumbled upon the execCommand:</p>
  
  <p>I'm using <code>document.execCommand("undo", false, null)</code>, but it doesn't work
  with Firefox.</p>
  
  <p>I put in the 2nd and 3rd parameters even though they are optional in Firefox.</p>
  
  <p>Any ideas, insights, suggestions, examples, etc?</p>