exit-on-double-back/src/ExitOnDoubleBack.component.android.js

Exits app when back button is pressed twice in the passed interval on the index route of react-navigation

/* ExitOnDoubleBack: Exits app when back button is pressed twice in the passed interval*/

import getCurrentRouteName from '../helpers/getCurrentRoute';
import PropTypes from 'prop-types';
import React, {Component} from 'react';
import {BackHandler, ToastAndroid} from 'react-native';
import noop from '../helpers/noop';

class ExitOnDoubleBack extends Component {
  componentWillMount () {
    BackHandler.addEventListener('hardwareBackPress', this._handleBackPress);
  }
  timer = {
    ref: null,
    isTimerRunning: false
  }
  _handleExit = () => {
    if (!this.timer.isTimerRunning) {
      this.timer.isTimerRunning = true;
      const backInterval = this.props.doubleBackInterval;
      clearTimeout(this.timer.ref);
      this.timer.ref = setTimeout(() => this.timer.isTimerRunning = false, backInterval);
      ToastAndroid.show(this.props.toastMessage, ToastAndroid.SHORT);
      return true; // don't do anything
    }
    return this.props.onDoubleBack && this.props.onDoubleBack();
  }

  _handleBackPress = () => {
    const {nav, backHandler} = this.props;
    const currentRoute = getCurrentRouteName(nav);
    if (this.props.exitableRoutes.includes(currentRoute)) { // exit the app from landing page
      return this._handleExit();
    } else { // in all the other cases, navigate back
      backHandler();
      return true;
    }
  }
  componentWillUnmount () {
    BackHandler.removeEventListener('hardwareBackPress', this._handleBackPress);
    clearTimeout(this.timer.ref);
    this.timer = {
      ref: null,
      isTimerRunning: false
    };
  }

  render () {
    return this.props.children;
  }
}
ExitOnDoubleBack.defaultProps = {
  toastMessage: 'Press back again to exit the app',
  doubleBackInterval: 3000,
  exitableRoutes: ['Landing'],
  onDoubleBack: BackHandler.exitApp,
  backHandler: noop,
  nav: {}
};
ExitOnDoubleBack.propTypes = {
  toastMessage: PropTypes.string,
  doubleBackInterval: PropTypes.number,
  exitableRoutes: PropTypes.array,
  children: PropTypes.node,
  onDoubleBack: PropTypes.func,
  backHandler: PropTypes.func,
  nav: PropTypes.object,
};
export default ExitOnDoubleBack;