title: Pure javascript div resize event
body: <p>I need you because I need to detect if a div is resizing and I just found some solution using JQuery and window.resize.</p>
  
  <p>The thing is that I don't want to use any library, and the window is not resizing. The div is resizing because a menu pop up. I could do that with a dispatch event on the menu, but I want my widget to work itself.</p>
  
  <p>JS FIDDLE :
  <a href="http://jsfiddle.net/b7mNU/3/" rel="nofollow noreferrer">http://jsfiddle.net/b7mNU/3/</a></p>
  
  <p>I want to get the onresize of the red rectangle without using the event on the menu (yellow div).
  Something like :</p>
  
  <pre><code>child.addEventListener('resize', function(){ /* do something */ }, false);
  </code></pre>