Обращение к имени переменной

class someComponent extends React.Component { 
  render() { 
    return ( 
      <div> 
        someComponent! {this.props.text} 
      </div> 
    ); 
  } 
} 
 
class anotherComponent extends React.Component { 
  render() { 
    return ( 
      <div> 
        anotherComponent! {this.props.text} 
      </div> 
    ); 
  } 
} 
 
class App extends React.Component { 
  constructor(props) { 
    super(props); 
  } 
   
  render() { 
    const map = { 
      someComponent: someComponent, 
      anotherComponent: anotherComponent, 
    } 
    const Component = map[this.props.currentScreen]; 
    const props = this.props.currentScreenProps; 
    if (!Component) return null; 
 
    return ( 
      <Component {...props} /> 
    ); 
  } 
} 
 
// const currentScreen = 'someComponent'; 
const currentScreen = 'anotherComponent'; 
const props = { text: 'Hello World'}; 
 
ReactDOM.render( 
  <App currentScreen={currentScreen} currentScreenProps={props} />, 
  document.getElementById('root') 
);

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script> 
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script> 
<div id="root"></div>