[webview_flutter]Adds support to intercept JavaScript alert/confirm/prompt dialog.

packages/webview_flutter/webview_flutter/CHANGELOG.md

@@ -1,3 +1,10 @@
+## 4.5.0
+
+* Adds support to intercept JavaScript dialog.
+  Sees `WebViewController.setOnJavaScriptAlertDialog`,
+  `WebViewController.setOnJavaScriptConfirmDialog`,
+  `WebViewController.setOnJavaScriptPromptDialog`.
+
 ## 4.4.1
 
 * Exposes `JavaScriptLogLevel` from platform interface.

packages/webview_flutter/webview_flutter/example/lib/main.dart

@@ -243,6 +243,9 @@ enum MenuOptions {
   transparentBackground,
   setCookie,
   logExample,
+  jsAlert,
+  jsConfirm,
+  jsPrompt,
 }
 
 class SampleMenu extends StatelessWidget {
@@ -302,6 +305,15 @@ class SampleMenu extends StatelessWidget {
           case MenuOptions.logExample:
             _onLogExample();
             break;
+          case MenuOptions.jsAlert:
+            _onJavaScriptAlertExample(context);
+            break;
+          case MenuOptions.jsConfirm:
+            _onJavaScriptConfirmExample(context);
+            break;
+          case MenuOptions.jsPrompt:
+            _onJavaScriptPromptExample(context);
+            break;
         }
       },
       itemBuilder: (BuildContext context) => <PopupMenuItem<MenuOptions>>[
@@ -362,6 +374,18 @@ class SampleMenu extends StatelessWidget {
           value: MenuOptions.logExample,
           child: Text('Log example'),
         ),
+        const PopupMenuItem<MenuOptions>(
+          value: MenuOptions.jsAlert,
+          child: Text('JavaScript Alert example'),
+        ),
+        const PopupMenuItem<MenuOptions>(
+          value: MenuOptions.jsConfirm,
+          child: Text('JavaScript Confirm example'),
+        ),
+        const PopupMenuItem<MenuOptions>(
+          value: MenuOptions.jsPrompt,
+          child: Text('JavaScript Prompt example'),
+        ),
       ],
     );
   }
@@ -481,6 +505,98 @@ class SampleMenu extends StatelessWidget {
     return webViewController.loadHtmlString(kTransparentBackgroundPage);
   }
 
+  Future<void> _onJavaScriptAlertExample(BuildContext context) {
+    webViewController.setOnJavaScriptAlertDialog((String message) async {
+      await showDialog(
+          context: context,
+          barrierDismissible: false,
+          builder: (
+            BuildContext context,
+          ) {
+            return AlertDialog(
+              content: Text(message),
+              actions: <Widget>[
+                TextButton(
+                    onPressed: () {
+                      Navigator.of(context).pop();
+                    },
+                    child: const Text('OK'))
+              ],
+            );
+          });
+    });
+    return webViewController
+        .runJavaScript("alert('This is a JavaScript alert dialog');");
+  }
+
+  Future<void> _onJavaScriptConfirmExample(BuildContext context) {
+    webViewController.setOnJavaScriptConfirmDialog((String message) async {
+      final bool? result = await showDialog<bool>(
+          context: context,
+          barrierDismissible: false,
+          builder: (BuildContext context) {
+            return AlertDialog(
+              content: Text(message),
+              actions: <Widget>[
+                TextButton(
+                  onPressed: () {
+                    Navigator.of(context).pop(true);
+                  },
+                  child: const Text('OK'),
+                ),
+                TextButton(
+                  onPressed: () {
+                    Navigator.of(context).pop(false);
+                  },
+                  child: const Text('Cancel'),
+                )
+              ],
+            );
+          });
+      debugPrint('result=$result');
+      return result ?? false;
+    });
+    return webViewController
+        .runJavaScript("confirm('This is a JavaScript confirm dialog');");
+  }
+
+  Future<void> _onJavaScriptPromptExample(BuildContext context) {
+    final TextEditingController textEditingController = TextEditingController();
+    webViewController.setOnJavaScriptPromptDialog(
+        (String message, String? defaultText) async {
+      textEditingController.text = defaultText ?? '';
+      final String? result = await showDialog<String>(
+          context: context,
+          barrierDismissible: false,
+          builder: (BuildContext context) {
+            return AlertDialog(
+              title: Text(message),
+              content: TextField(
+                controller: textEditingController,
+              ),
+              actions: <Widget>[
+                TextButton(
+                  onPressed: () {
+                    Navigator.of(context).pop(textEditingController.text);
+                  },
+                  child: const Text('OK'),
+                ),
+                TextButton(
+                  onPressed: () {
+                    Navigator.of(context).pop('');
+                  },
+                  child: const Text('Cancel'),
+                )
+              ],
+            );
+          });
+      debugPrint('result=$result');
+      return result ?? '';
+    });
+    return webViewController
+        .runJavaScript("prompt('This is a JavaScript prompt dialog');");
+  }
+
   Widget _getCookieList(String cookies) {
     if (cookies == '""') {
       return Container();

packages/webview_flutter/webview_flutter/lib/src/webview_controller.dart

@@ -370,6 +370,28 @@ class WebViewController {
     return platform.setOnConsoleMessage(onConsoleMessage);
   }
 
+  /// Sets a callback that notifies the host application that the web page
+  /// wants to display a JavaScript alert() dialog.
+  Future<void> setOnJavaScriptAlertDialog(
+      Future<void> Function(String message) onJavaScriptAlertDialog) async {
+    return platform.setOnJavaScriptAlertDialog(onJavaScriptAlertDialog);
+  }
+
+  /// Sets a callback that notifies the host application that the web page
+  /// wants to display a JavaScript confirm() dialog.
+  Future<void> setOnJavaScriptConfirmDialog(
+      Future<bool> Function(String message) onJavaScriptConfirmDialog) async {
+    return platform.setOnJavaScriptConfirmDialog(onJavaScriptConfirmDialog);
+  }
+
+  /// Sets a callback that notifies the host application that the web page
+  /// wants to display a JavaScript prompt() dialog.
+  Future<void> setOnJavaScriptPromptDialog(
+      Future<String> Function(String message, String? defaultText)
+          onJavaScriptPromptDialog) async {
+    return platform.setOnJavaScriptPromptDialog(onJavaScriptPromptDialog);
+  }
+
   /// Gets the value used for the HTTP `User-Agent:` request header.
   Future<String?> getUserAgent() {
     return platform.getUserAgent();

packages/webview_flutter/webview_flutter/pubspec.yaml

@@ -2,7 +2,7 @@ name: webview_flutter
 description: A Flutter plugin that provides a WebView widget on Android and iOS.
 repository: https://github.com/flutter/packages/tree/main/packages/webview_flutter/webview_flutter
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+webview%22
-version: 4.4.1
+version: 4.5.0
 
 environment:
   sdk: ">=2.19.0 <4.0.0"

packages/webview_flutter/webview_flutter_android/CHANGELOG.md

@@ -1,3 +1,10 @@
+## 3.13.0
+
+* Adds support to intercept JavaScript dialog.
+  Sees `PlatformWebViewController.setOnJavaScriptAlertDialog`,
+  `PlatformWebViewController.setOnJavaScriptConfirmDialog`,
+  `PlatformWebViewController.setOnJavaScriptPromptDialog`.
+
 ## 3.12.0
 
 * Adds support for `PlatformWebViewController.getUserAgent`.

packages/webview_flutter/webview_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/GeneratedAndroidWebView.java

@@ -2620,6 +2620,15 @@ void setSynchronousReturnValueForOnShowFileChooser(
     void setSynchronousReturnValueForOnConsoleMessage(
         @NonNull Long instanceId, @NonNull Boolean value);
 
+    void setSynchronousReturnValueForOnJsAlert(
+            @NonNull Long instanceId, @NonNull Boolean value);
+
+    void setSynchronousReturnValueForOnJsConfirm(
+            @NonNull Long instanceId, @NonNull Boolean value);
+
+    void setSynchronousReturnValueForOnJsPrompt(
+            @NonNull Long instanceId, @NonNull Boolean value);
+
     /** The codec used by WebChromeClientHostApi. */
     static @NonNull MessageCodec<Object> getCodec() {
       return new StandardMessageCodec();
@@ -2709,6 +2718,81 @@ static void setup(
           channel.setMessageHandler(null);
         }
       }
+      {
+        BasicMessageChannel<Object> channel =
+                new BasicMessageChannel<>(
+                        binaryMessenger, "dev.flutter.pigeon.webview_flutter_android.WebChromeClientHostApi.setSynchronousReturnValueForOnJsAlert", getCodec());
+        if (api != null) {
+          channel.setMessageHandler(
+                  (message, reply) -> {
+                    ArrayList<Object> wrapped = new ArrayList<Object>();
+                    ArrayList<Object> args = (ArrayList<Object>) message;
+                    Number instanceIdArg = (Number) args.get(0);
+                    Boolean valueArg = (Boolean) args.get(1);
+                    try {
+                      api.setSynchronousReturnValueForOnJsAlert((instanceIdArg == null) ? null : instanceIdArg.longValue(), valueArg);
+                      wrapped.add(0, null);
+                    }
+                    catch (Throwable exception) {
+                      ArrayList<Object> wrappedError = wrapError(exception);
+                      wrapped = wrappedError;
+                    }
+                    reply.reply(wrapped);
+                  });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
+      {
+        BasicMessageChannel<Object> channel =
+                new BasicMessageChannel<>(
+                        binaryMessenger, "dev.flutter.pigeon.webview_flutter_android.WebChromeClientHostApi.setSynchronousReturnValueForOnJsConfirm", getCodec());
+        if (api != null) {
+          channel.setMessageHandler(
+                  (message, reply) -> {
+                    ArrayList<Object> wrapped = new ArrayList<Object>();
+                    ArrayList<Object> args = (ArrayList<Object>) message;
+                    Number instanceIdArg = (Number) args.get(0);
+                    Boolean valueArg = (Boolean) args.get(1);
+                    try {
+                      api.setSynchronousReturnValueForOnJsConfirm((instanceIdArg == null) ? null : instanceIdArg.longValue(), valueArg);
+                      wrapped.add(0, null);
+                    }
+                    catch (Throwable exception) {
+                      ArrayList<Object> wrappedError = wrapError(exception);
+                      wrapped = wrappedError;
+                    }
+                    reply.reply(wrapped);
+                  });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
+      {
+        BasicMessageChannel<Object> channel =
+                new BasicMessageChannel<>(
+                        binaryMessenger, "dev.flutter.pigeon.webview_flutter_android.WebChromeClientHostApi.setSynchronousReturnValueForOnJsPrompt", getCodec());
+        if (api != null) {
+          channel.setMessageHandler(
+                  (message, reply) -> {
+                    ArrayList<Object> wrapped = new ArrayList<Object>();
+                    ArrayList<Object> args = (ArrayList<Object>) message;
+                    Number instanceIdArg = (Number) args.get(0);
+                    Boolean valueArg = (Boolean) args.get(1);
+                    try {
+                      api.setSynchronousReturnValueForOnJsPrompt((instanceIdArg == null) ? null : instanceIdArg.longValue(), valueArg);
+                      wrapped.add(0, null);
+                    }
+                    catch (Throwable exception) {
+                      ArrayList<Object> wrappedError = wrapError(exception);
+                      wrapped = wrappedError;
+                    }
+                    reply.reply(wrapped);
+                  });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
     }
   }
   /** Generated interface from Pigeon that represents a handler of messages from Flutter. */
@@ -2862,6 +2946,57 @@ public void onShowFileChooser(
             callback.reply(output);
           });
     }
+    public void onJsAlert(
+        @NonNull Long instanceIdArg,
+        @NonNull String messageArg,
+        @NonNull Reply<Void> callback) {
+      BasicMessageChannel<Object> channel =
+          new BasicMessageChannel<>(
+              binaryMessenger,
+              "dev.flutter.pigeon.webview_flutter_android.WebChromeClientFlutterApi.onJsAlert", 
+              getCodec());
+      channel.send(
+          new ArrayList<Object>(
+              Arrays.asList(instanceIdArg, messageArg)),
+          channelReply -> callback.reply(null));
+    }
+    public void onJsConfirm(
+        @NonNull Long instanceIdArg,
+        @NonNull String messageArg,
+        @NonNull Reply<Boolean> callback) {
+      BasicMessageChannel<Object> channel =
+          new BasicMessageChannel<>(
+              binaryMessenger,
+              "dev.flutter.pigeon.webview_flutter_android.WebChromeClientFlutterApi.onJsConfirm",
+              getCodec());
+      channel.send(
+          new ArrayList<Object>(
+              Arrays.asList(instanceIdArg, messageArg)),
+          channelReply -> {
+            @SuppressWarnings("ConstantConditions")
+            Boolean output = (Boolean) channelReply;
+            callback.reply(output);
+          });
+    }
+    public void onJsPrompt(
+        @NonNull Long instanceIdArg,
+        @NonNull String messageArg,
+        @NonNull String defaultValueArg,
+        @NonNull Reply<String> callback) {
+      BasicMessageChannel<Object> channel =
+          new BasicMessageChannel<>(
+              binaryMessenger,
+              "dev.flutter.pigeon.webview_flutter_android.WebChromeClientFlutterApi.onJsPrompt",
+              getCodec());
+      channel.send(
+          new ArrayList<Object>(
+              Arrays.asList(instanceIdArg, messageArg, defaultValueArg)),
+          channelReply -> {
+            @SuppressWarnings("ConstantConditions")
+            String output = (String) channelReply;
+            callback.reply(output);
+          });
+    }
     /** Callback to Dart function `WebChromeClient.onPermissionRequest`. */
     public void onPermissionRequest(
         @NonNull Long instanceIdArg,