React Base Fiddle (JSX)

Starting point for creating JSFiddles with React.

HTML

<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
<div id="container">
    <!-- This element's contents will be replaced with your component. -->
</div>

Babel + JSX

function UnrenderedComponent() {
      console.log("UnrenderedComponent does not get executed");

      React.useEffect(() => {
        console.log("this effect never runs")
      });

      return "This won't get rendered"
    }

    function RenderedComponent() {
      console.log("Rendered Component running")

      React.useEffect(() => {
        console.log("this effect runs")
      });

      const x = <UnrenderedComponent/>;

      return "This will get rendered";
    }


    ReactDOM.render(
      <RenderedComponent />,
      document.getElementById('container')
    );