mutationobserver.js

// http://www.w3.org/TR/dom/
// http://updates.html5rocks.com/2012/02/Detect-DOM-changes-with-Mutation-Observers
// https://developer.mozilla.org/en-US/docs/DOM/MutationObserver
var MutationObserver = (function () {
  var prefixes = ['WebKit', 'Moz', 'O', 'Ms', '']
  for(var i=0; i < prefixes.length; i++) {
    if(prefixes[i] + 'MutationObserver' in window) {
      return window[prefixes[i] + 'MutationObserver'];
    }
  }
  return false;
}());

if(MutationObserver) {
  // Use MutationObserver
}
else {
  // Fallback
}