content);
    if (item.content != null) {
      callback(item); // send back adjusted item
    }
    else {
      callback(null); // cancel updating the item
    }
  }
};
</pre>

  A full example is available here: <a href="../../examples/timeline/editing/editingItemsCallbacks.html">editingItemsCallbacks.html</a>.


  <h2 id="Templates">Templates</h2>

  <p>
    Timeline supports templates to format item contents. Any template engine (such as <a href="http://handlebarsjs.com/">handlebars</a> or <a href="htt