title: React lifecycle method when component is fully rendered
body: <p>I need to do some size calculations when a component is fully rendered. The <code>componentDidMount</code> method, however fires as soon as the component is rendered, but it's children are not. This code for example:</p>
  
  <pre><code>componentDidMount(){
    console.log(findDOMNode(this).childNodes.length);
  }
  </code></pre>
  
  <p>outputs <code>0</code></p>
  
  <p>What is the proper way to trigger some code once a component has been fully rendered, together with any descendant components.</p>
  
  <p>Edit: I don't want to use <code>componentDidUpdate</code> since that method fires on any update. I just need this to be run once.</p>
  
  <p>Edit2: As @NaisheelVerdhan points out, the docs say that <code>componentDidMount</code> ins invoked on children first, but in this case I'm confused as to why my above example returns <code>0</code></p>