App_2.10.js

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 *
 * @format
 * @flow strict-local
 */

 import React from 'react';
 import {
   SafeAreaView,
   StyleSheet,
   ScrollView,
   View,
   Text,
   StatusBar,
 } from 'react-native';
 
 import {
   Header,
   LearnMoreLinks,
   Colors,
   DebugInstructions,
   ReloadInstructions,
 } from 'react-native/Libraries/NewAppScreen';
 
 class App extends Component {
   constructor(){
     super()
     this.state = {
       book: 'React Native in Action'
     }
   }
   updateBook() {
     this.setState({
     book: 'Express in Action'
     })
   }
   render() {
     return (
       <BookDisplay 
        updateBook={ () => this.updateBook() } 
        book={ this.state.book } />
     )
   }
 }
 class BookDisplay extends Component {
   render() {
     return (
       <View>
         <Text onPress={ this.props.updateBook }>
           { this.props.book }
         </Text>
       </View>
     )
   }
 }
 
 export default App;