JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://unpkg.com/[email protected]/dist/react.js"></script>
<script src="https://unpkg.com/[email protected]/dist/react-dom.js"></script>
<div id="app">

</div>

CSS

#app {
  margin-top: 20px;
}

Babel + JSX

class App extends React.Component {
  constructor(props) {
    super(props);
    this.handleKeyPress = this.handleKeyPress.bind(this);
  }
  handleKeyPress(e) {
  console.log(e.nativeEvent)
  console.log(e.nativeEvent.shiftKey)
    if (e.nativeEvent.keyCode === 13) {         
        if(e.nativeEvent.shiftKey){
            $('#app').append("<br/> Shift + Enter")
        }
    }
  }
  render() {
    return ( < textarea defaultValue = {
        ""
      }
      onKeyUp = {
        this.handleKeyPress
      }
      onKeyDown = {
      	this.handleKeyPress
      }
      />
    );
  }
}

ReactDOM.render(<App/>, document.getElementById('app'));