Closed
Description
Steps to reproduce
- register javascript channel in webview controller
- load page that will eventually send undefined message to this channel
Expected results
onMessageReceived callback should receive instance of JavascriptMessage with 'undefined' message as a string.
Actual results
App crashes with an exception
Code sample
After 5 seconds js will send deadly command to application.
Code sample
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
WebViewController controller = WebViewController()
..setJavaScriptMode(JavaScriptMode.unrestricted)
..addJavaScriptChannel('Channel', onMessageReceived: (message) {
print('Received message: ${message.toString()}');
});
NavigationDelegate navigationDelegate = NavigationDelegate(
onPageFinished: (String url) {
controller.runJavaScript("""
var i=3;
setInterval(() => {
document.body.textContent = 'Crash in ' + i;
--i;
}, 1000);
setTimeout(() => {
window.Channel.postMessage(undefined);
}, 5000);
""");
},
);
controller.setNavigationDelegate(navigationDelegate);
controller.loadHtmlString('<html><body>Test</body></html>');
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: const Text('60km/h crash test')),
body: WebViewWidget(controller: controller),
)
);
}
}Screenshots or Video
Screenshots / Video demonstration
Simulator.Screen.Recording.-.iPhone.SE.3rd.generation.-.2025-01-29.at.00.56.08.mp4
Logs
Logs
webview_flutter_wkwebview/ProxyAPIRegistrar.swift:71: Fatal error: webview_flutter_wkwebview.PigeonError: Error returned from calling WKScriptMessageHandler.didReceiveScriptMessage: Optional("Null check operator used on a null value")Flutter Doctor output
Doctor output
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.27.3, on macOS 15.1.1 24B91 darwin-arm64, locale pl-PL)
[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0-rc4)
[✓] Xcode - develop for iOS and macOS (Xcode 16.2)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2024.1)
[✓] VS Code (version 1.96.4)
[✓] Connected device (5 available)
[✓] Network resources
• No issues found!Metadata
Metadata
Assignees
Labels
Crashes that terminate the processFound to occur in 3.27Found to occur in 3.29The issue has been confirmed reproducible and is ready to work onThe WebView pluginflutter/packages repository. See also p: labels.iOS applications specificallyIssue is closed as already fixed in a newer versionOwned by Ecosystem team