title: setting a single property using setState for an object in reactJS
body: <p>I'm trying to update the property 'name' of my object person using setState. But it doesn't seem to work. 
  I'm getting the 'newName' through user input.</p>
  
  <p>What am I missing here?</p>
  
  <pre><code>this.setState({ person: { name: newName } });
  </code></pre>