React-native: WebView not updated with injected javascript SOLVED

[Hyllesen]

Description

I'm having trouble updating the webview using React Native when there is injected Javascript code.
This example does not update the counter in the webview when the highlight is pressed.

Reproduction

'use strict';
import React, { Component } from 'react';
import {
  StyleSheet,
  View,
  Image,
  Text,
  TouchableHighlight,
  WebView
} from 'react-native';

export default class WebViewTest extends Component {

  constructor(props) {
    super(props);
    this.state = {
    timesClicked : 0
  };
  this._onPressButton = this._onPressButton.bind(this);
  this.generateJSCode = this.generateJSCode.bind(this);
  }

  _onPressButton() {
    let timesClicked = this.state.timesClicked++;
    console.log(timesClicked + " Clicked ");
    this.setState({
      timesClicked: this.state.timesClicked++
    });
  }

  generateJSCode() {
    console.log("Times clicked: " + this.state.timesClicked);
    let jsCode = `document.getElementById("content").innerHTML = "HTML Times clicked: ${this.state.timesClicked}";`;
    return jsCode;
  }

  render() {
    let html = `
        <div id="content">
            This is my name
        </div>
    `;

    return (
        <View style={styles.container}>
          <TouchableHighlight onPress={this._onPressButton}>
            <Text>Press me to increase click</Text>
          </TouchableHighlight>
          <Text>React Native times clicked: {this.state.timesClicked}</Text>
            <WebView
                style={styles.webView}
                source={{html : html}}
                injectedJavaScript={this.generateJSCode()}
                javaScriptEnabledAndroid={true}
            >
            </WebView>
        </View>
    );
  }
}

let styles = StyleSheet.create({
container: {
    flex: 1,
    backgroundColor: '#fff',
    margin: 30
},
webView: {
    backgroundColor: '#fff',
    height: 350,
}
});

Additional Information

• React Native version: 0.39
• Platform: iOS
• Operating System: MacOS

Solution

Solution is to use messsages instead of injecting javascript, like so:

// @flow
'use strict';
import React, { Component } from 'react';
import {
  StyleSheet,
  View,
  Image,
  Text,
  TouchableHighlight,
  WebView
} from 'react-native';

export default class WebViewTest extends Component {

  constructor(props) {
    super(props);
    this.state = {
    timesClicked : 0
  };
  this._onPressButton = this._onPressButton.bind(this);
  }

  _onPressButton() {
    let timesClicked = this.state.timesClicked;
    timesClicked++;
    console.log(timesClicked + " Clicked ");
    this.setState({
      timesClicked: timesClicked
    });
    this.refs.myWebView.postMessage("This is my land times " + timesClicked);
  }

  render() {
    let html = `
        <div id="content">
            This is my name
        </div>
        <script>
          document.addEventListener('message', function(e) {
            document.getElementById("content").innerHTML = e.data;
          });
        </script>
    `;

    return (
        <View style={styles.container}>
          <TouchableHighlight onPress={this._onPressButton}>
            <Text>Press me to increase click</Text>
          </TouchableHighlight>
          <Text>React Native times clicked: {this.state.timesClicked}</Text>
            <WebView
                style={styles.webView}
                source={{html : html}}
                ref="myWebView"
                javaScriptEnabledAndroid={true}
                onMessage={this.onMessage}
            >
            </WebView>
        </View>
    );
  }
}

let styles = StyleSheet.create({
container: {
    flex: 1,
    backgroundColor: '#fff',
    margin: 30
},
webView: {
    backgroundColor: '#fff',
    height: 350,
}
});

[eshwartm]

Where is onMessage defined from this.onMessage?

[hramos]

Hi there! This issue is being closed because it has been inactive for a while. Maybe the issue has been fixed in a recent release, or perhaps it is not affecting a lot of people. Either way, we're automatically closing issues after a period of inactivity. Please do not take it personally!

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If you would like to work on a patch to fix the issue, contributions are very welcome! Read through the contribution guide, and feel free to hop into #react-native if you need help planning your contribution.

[savioseb]

@eshwartm
Refer to https://facebook.github.io/react-native/docs/webview.html#onmessage for onMessage

To see how it is implemented check: https://stackoverflow.com/questions/41260270/updating-webview-javascript-in-react-native

[reedspool]

@eshwartm In @Hyllesen's example, this.onMessage is never defined, so the onMessage prop is set to undefined. But within the html, window.postMessage is never used either, so it's only a one-way bridge, sending into the WebView but not out.

[reedspool]

@Hyllesen your injectedJavaScript would work if you used this.generateJSCode.toString() instead of this.generateJSCode(), although you can't access this.state inside the WebView environment, so you'd get a "unable to access timesClicked on undefined" error.