title: Load block's content with AJAX
body: <p>What is the best way, installing as few modules as possible, to load content into a custom block?</p>
  
  <p>My understanding is that an easy way to do it is by creating a page callback that calls <code>drupal_json_output()</code> and then add a Drupal JavaScript behavior to query that page and receive the JSON content.</p>
  
  <p>Are there better ways? Is there any already built-in functionality?</p>