DOM Mutation Listener - Google Maps

domlistener.js

  var observeDOM = (function(){
      var MutationObserver = window.MutationObserver || window.WebKitMutationObserver,
          eventListenerSupported = window.addEventListener;

      return function(obj, callback){
          if( MutationObserver ){
              // define a new observer
              var obs = new MutationObserver(function(mutations, observer){
                  if( mutations[0].addedNodes.length || mutations[0].removedNodes.length )
                      callback();
              });
              // have the observer observe foo for changes in children
              obs.observe( obj, { childList:true, subtree:true });
          }
          else if( eventListenerSupported ){
              obj.addEventListener('DOMNodeInserted', callback, false);
              obj.addEventListener('DOMNodeRemoved', callback, false);
          }
      };
  })();

  // Observe a specific DOM element:
  var main = document.getElementById('elm-main');
  observeDOM(main ,function(){ 
    var map = document.getElementById('map');
    if (map && main.contains(map) && !map.hasChildNodes()) {
      initMap();
    }
  });