title: Javascript: document.execCommand cross-browser?
body: <p>I just stumble on a piece of code which I never saw before:</p>
  
  <p><code>document.execCommand('Copy');</code></p>
  
  <p>which seems to copy the clipboard contents to the element in focus.</p>
  
  <p>Is this functionality available cross-browser?</p>
  
  <hr>
  
  <p>I found <a href="http://www.quirksmode.org/dom/execCommand.html" rel="noreferrer">a page</a> that shows a compatibility matrix for <code>document.execCommand</code>.</p>