title: React: default proprerty of an object
body: <p>Currently I'm going through a React course, and today I met an issue.</p>
  <p>I import a component dynamically. I don't get what's the meaning of <code>default</code> in this snippet:</p>
  <pre><code>    componentDidMount() {
          importComponent()
              .then (cmp =&gt; {
                  this.setState({component: cmp.default})
              })
      }
  </code></pre>
  <p>What is <code>cmp.default</code> about?</p>