title: How to sync frontend model with backend database
body: <p>Take a "todo app" for example. As I add/remove items, or mark items as done, I want the frontend to automatically send ajax updates.</p>
  
  <p>Also, if the backend were to change because somebody else added a new todo item, I want the frontend to update.</p>
  
  <p>I know the <code>meteor</code> framework does this. Are there any non-framework options? (libraries)</p>