title: why alert is not display while using pure function in react?
body: <p><a href="https://plnkr.co/edit/eCZSo6Rl5odN1hTb6BCW?p=preview" rel="nofollow noreferrer">https://plnkr.co/edit/eCZSo6Rl5odN1hTb6BCW?p=preview</a></p>
  
  <p>Hi</p>
  
  <p>i am implementing row <code>component</code> which will add when user fill item in input field and press <code>add</code> button</p>
  
  <pre><code>var listItems = this.props.names.map(function(d, idx){
        return (&lt;r key={idx}&gt;&lt;/r&gt;)
      })
  </code></pre>
  
  <p>but it not show alert when we try to add component </p>
  
  <pre><code>const r = (props) =&gt; {
      alert('---')
      return (
          &lt;li&gt;
              &lt;span&gt;hiii&lt;/span&gt;
          &lt;/li&gt;
      );
  };
  </code></pre>
  
  <p>any update ??</p>