title: Can I update a component's props in React.js?
body: <p>After starting to work with React.js, it seems like <code>props</code> are intended to be static (passed in from the parent component), while <code>state</code> changes based upon events.  However, I noticed in the docs a reference to <a href="http://facebook.github.io/react/docs/component-specs.html#updating-componentwillreceiveprops"><code>componentWillReceiveProps</code></a>, which specifically includes this example:</p>
  
  <pre><code>componentWillReceiveProps: function(nextProps) {
    this.setState({
      likesIncreasing: nextProps.likeCount &gt; this.props.likeCount
    });
  }
  </code></pre>
  
  <p>This seems to imply that the properties CAN change on a component based upon the comparison of <code>nextProps</code> to <code>this.props</code>.  What am I missing?  How do props change, or am I mistaken about where this gets called?</p>