React Native: Handle hardware back button @ webview

webview.js

import * as React from 'react';
import { BackHandler  } from 'react-native';
import { WebView } from 'react-native-webview';

export default class App extends React.Component {

  constructor(props) {
      super(props);
      this.WEBVIEW_REF = React.createRef();
    }

    componentDidMount() {
      BackHandler.addEventListener('hardwareBackPress', this.handleBackButton);
    }

    componentWillUnmount() {
      BackHandler.removeEventListener('hardwareBackPress', this.handleBackButton);
    }

    handleBackButton = ()=>{
      this.WEBVIEW_REF.current.goBack();
      return true;
    }

    onNavigationStateChange(navState) {
      this.setState({
        canGoBack: navState.canGoBack
      });
    }



  render() {
    return <WebView source={{ uri: 'https://www.mywebsite.xyz' }}
                    style={{ marginTop: 15}}
                    ref={this.WEBVIEW_REF}
                    onNavigationStateChange={this.onNavigationStateChange.bind(this)}
                    />;
  }

  }