title: When is React.render() callback called?
body: <pre><code>React.render(&lt;MyComponent/&gt;, mainNode, function() {
      console.log('2');
  });
  console.log('1');
  </code></pre>
  
  <p>prints</p>
  
  <pre><code>2
  1
  </code></pre>
  
  <p>Also, a scrollTop() in the callback does not work. It works if I call it after render() returns.</p>
  
  <p>Is React.render() synchronous?</p>
  
  <p>Is the DOM rendered when the function returns?</p>
  
  <p>When is the callback called? What would I want to do in the callback?</p>