[Aetae]

function observeChildNodes(where, fn) {
  var config = {
    childList: true,
    subtree: true
  };

  var insert = {
    type: "insert",
    nodes: []
  };
  var remove = {
    type: "remove",
    nodes: []
  };
  var observer = new MutationObserver(function(mutations) {

    mutations.forEach(function(mutation) {
      if(mutation.addedNodes.length){
        insert.nodes = insert.nodes.concat(mutation.addedNodes);            
      }
      if(mutation.removedNodes.length){
        remove.nodes = remove.nodes.concat(mutation.removedNodes);
      }
    });
    if(remove.nodes.length)
      fn(remove);
    if(insert.nodes.length)
      fn(insert);
  });


  observer.observe(where, config);
}