How do I go back in webview? I am using the react-navigation package in react-native

问题

I installed the react-navigation package in react-native

I have implemented tab navigation and one of them is implemented in webview format.

My problem is that if I press the back physical button on Android, I go from the app itself to the previous tab, not back from the webview.

I've already applied the back button for the webview on the internet, but I have not done that.

I tried to display the onNavigationStateChange log when debugging, but it was not updated when url was moved after it was loaded at first startup. Here is the code I implemented:

import React from "react";
import {BackHandler} from "react-native";
import {WebView} from "react-native-webview";

class SermonScreen extends React.Component {
    constructor(props) {
        super(props);
    }
    static navigationOptions = {
        header: null
    };

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

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

    _onNavigationStateChange(navState) {
        console.log(navState);
        this.setState({
            canGoBack: navState.canGoBack
        });
    }

    handleBackButton = () => {
        console.log(this.state);
        if (this.state.canGoBack === true) {
            this.webView.goBack();
            return true;
        } else {
            return false;
        }
    };

    render() {
        return (
            <WebView
                source={{uri: 'https://m.youtube.com/channel/UCw3kP3qCCF7ZpLUNzm_Q9Xw/videos' }}
                ref={(webView) => this.webView = webView}
                onNavigationStateChange={this._onNavigationStateChange.bind(this)}
            />
        );
    }
}

export default SermonScreen;

回答1:

Following the official webview documnentation you could try to do this: https://github.com/react-native-community/react-native-webview/blob/master/docs/Guide.md#intercepting-hash-url-changes

In general you were almost there, however the way the YT navigation works made it impossible to be caught via the onNavigationStateChange, that's why we inject a JS code that intercepts these hash changes and posts a message to the parent component, we then catch it inside the onMessage handler and set the state variable properly. Copying the injectedJavaScript and onMessage properties to your example should solve your problem.

I prepared a component for you that seems to do what is needed:

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

import React, { Fragment } from "react";
import {
  SafeAreaView,
  StyleSheet,
  ScrollView,
  View,
  Text,
  BackHandler,
  StatusBar
} from "react-native";
import { WebView } from "react-native-webview";
import {
  Header,
  LearnMoreLinks,
  Colors,
  DebugInstructions,
  ReloadInstructions
} from "react-native/Libraries/NewAppScreen";

class App extends React.Component {
  constructor(props) {
    super(props);
    this.startingUrl =
      "https://m.youtube.com/channel/UCw3kP3qCCF7ZpLUNzm_Q9Xw/videos";
    this.handleBackButton = this.handleBackButton.bind(this);
  }

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

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

  handleBackButton = () => {
    console.log(this.state);
    const { canGoBack } = this.state;
    if (canGoBack) {
      this.webView.goBack();
      return true;
    } else {
      return false;
    }
  };

  render() {
    return (
      <Fragment>
        <WebView
          source={{ uri: this.startingUrl }}
          style={{ marginTop: 20 }}
          ref={webView => (this.webView = webView)}
          injectedJavaScript={`
          (function() {
            function wrap(fn) {
              return function wrapper() {
                var res = fn.apply(this, arguments);
                window.ReactNativeWebView.postMessage('navigationStateChange');
                return res;
              }
            }

            history.pushState = wrap(history.pushState);
            history.replaceState = wrap(history.replaceState);
            window.addEventListener('popstate', function() {
              window.ReactNativeWebView.postMessage('navigationStateChange');
            });
          })();

          true;
        `}
          onMessage={({ nativeEvent: state }) => {
            if (state.data === "navigationStateChange") {
              // Navigation state updated, can check state.canGoBack, etc.
              this.setState({
                canGoBack: state.canGoBack
              });
            }
          }}
        />
      </Fragment>
    );
  }
}

export default App;

来源：https://stackoverflow.com/questions/55122592/how-do-i-go-back-in-webview-i-am-using-the-react-navigation-package-in-react-na