How to close React Native App using BackHandler API

Device back button handling

When you want your app to be able to exit using the back handler, the react native BackHandler api is used to make this happen. Here is two example codes, one for class based component and one for fictional based component.

For class based component Here is the code

 import { BackHandler } from 'react-native';

 constructor() {
        super();           
        this.handleBackButtonClick = this.handleBackButtonClick.bind(this);
 }
   componentWillMount() {
       BackHandler.addEventListener('hardwareBackPress', this.handleBackButtonClick);
   }
   componentWillUnmount() {
       BackHandler.removeEventListener('hardwareBackPress', this.handleBackButtonClick);
   }
   handleBackButtonClick() {
       BackHandler.exitApp();
       return true;
   }

For functional based component here is a good example

import { BackHandler } from 'react-native';

useEffect(() => {
    BackHandler.addEventListener("hardwareBackPress", handleBackButtonClick);
    return () => {
      BackHandler.removeEventListener(
        "hardwareBackPress",
        handleBackButtonClick
      );
    };
  }, []);