title: Why set property equal to itself in DOM render - React.js
body: <p>consider this block of code from <a href="http://facebook.github.io/react/docs/lists-and-keys.html" rel="nofollow noreferrer">http://facebook.github.io/react/docs/lists-and-keys.html</a></p>
  
  <pre><code>function ListItem(props) {
    // Correct! There is no need to specify the key here:
    return &lt;li&gt;{props.value}&lt;/li&gt;;
  }
  
  function NumberList(props) {
    const numbers = props.numbers;
    const listItems = numbers.map((number) =&gt;
      // Correct! Key should be specified inside the array.
      &lt;ListItem key={number.toString()}
                value={number} /&gt;
    );
    return (
      &lt;ul&gt;
        {listItems}
      &lt;/ul&gt;
    );
  }
  
  const numbers = [1, 2, 3, 4, 5];
  ReactDOM.render(
    &lt;NumberList numbers={numbers} /&gt;,
    document.getElementById('root')
  );
  </code></pre>
  
  <p>My question is, where you see:</p>
  
  <pre><code>&lt;NumberList numbers={numbers} /&gt;
  </code></pre>
  
  <p>I understand this is a component that is being rendered and we are giving it a property that we've created, but what is the significance of setting that property equal to itself? It has me a little confused.</p>
  
  <p>Thank you!</p>