Prevent JS prompts during page loading (#20)

Block JS prompts during page loading.

Patch ported from here MetaMask/metamask-mobile@5ee210a

Author: jpcloureiro

android/src/main/java/com/reactnativecommunity/webview/RNCWebChromeClient.java

@@ -15,6 +15,7 @@
 import android.view.ViewGroup;
 import android.webkit.ConsoleMessage;
 import android.webkit.GeolocationPermissions;
+import android.webkit.JsPromptResult;
 import android.webkit.PermissionRequest;
 import android.webkit.ValueCallback;
 import android.webkit.WebChromeClient;
@@ -59,6 +60,9 @@ public class RNCWebChromeClient extends WebChromeClient implements LifecycleEven
     protected View mVideoView;
     protected WebChromeClient.CustomViewCallback mCustomViewCallback;
 
+    // This boolean block JS prompts and alerts from displaying during loading
+    protected boolean blockJsDuringLoading = true;
+
     /*
      * - Permissions -
      * As native permissions are asynchronously handled by the PermissionListener, many fields have
@@ -383,6 +387,16 @@ public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathC
         return this.mWebView.getThemedReactContext().getNativeModule(RNCWebViewModule.class).startPhotoPickerIntent(filePathCallback, acceptTypes, allowMultiple, fileChooserParams.isCaptureEnabled());
     }
 
+    @Override
+    public boolean onJsPrompt(WebView view, String url, String message, String defaultValue, JsPromptResult result) {
+        if (blockJsDuringLoading) {
+            result.cancel();
+            return true;
+        } else {
+            return super.onJsPrompt(view, url, message, defaultValue, result);
+        }
+    }
+
     @Override
     public void onHostResume() {
         if (mVideoView != null && mVideoView.getSystemUiVisibility() != FULLSCREEN_SYSTEM_UI_VISIBILITY) {

android/src/main/java/com/reactnativecommunity/webview/RNCWebViewClient.java

@@ -9,6 +9,7 @@
 import android.webkit.HttpAuthHandler;
 import android.webkit.RenderProcessGoneDetail;
 import android.webkit.SslErrorHandler;
+import android.webkit.WebChromeClient;
 import android.webkit.WebResourceRequest;
 import android.webkit.WebResourceResponse;
 import android.webkit.WebView;
@@ -32,6 +33,7 @@
 import com.reactnativecommunity.webview.events.TopRenderProcessGoneEvent;
 import com.reactnativecommunity.webview.events.TopShouldStartLoadWithRequestEvent;
 
+import java.util.Objects;
 import java.util.concurrent.atomic.AtomicReference;
 
 public class RNCWebViewClient extends WebViewClient {
@@ -58,6 +60,9 @@ public void onPageFinished(WebView webView, String url) {
         if (!mLastLoadFailed) {
             RNCWebView reactWebView = (RNCWebView) webView;
 
+            RNCWebChromeClient webChromeClient = (RNCWebChromeClient) reactWebView.getWebChromeClient();
+            if(Objects.nonNull(webChromeClient)) webChromeClient.blockJsDuringLoading = false;
+
             reactWebView.callInjectedJavaScript();
 
             emitFinishEvent(webView, url);
@@ -81,12 +86,20 @@ public void onPageStarted(WebView webView, String url, Bitmap favicon) {
       mLastLoadFailed = false;
 
       RNCWebView reactWebView = (RNCWebView) webView;
+
+      RNCWebChromeClient webChromeClient = (RNCWebChromeClient) reactWebView.getWebChromeClient();
+      if(Objects.nonNull(webChromeClient)) webChromeClient.blockJsDuringLoading = true;
+
       reactWebView.callInjectedJavaScriptBeforeContentLoaded();
     }
 
     @Override
     public boolean shouldOverrideUrlLoading(WebView view, String url) {
         final RNCWebView rncWebView = (RNCWebView) view;
+
+        RNCWebChromeClient webChromeClient = (RNCWebChromeClient) rncWebView.getWebChromeClient();
+        if(Objects.nonNull(webChromeClient)) webChromeClient.blockJsDuringLoading = true;
+
         final boolean isJsDebugging = ((ReactContext) view.getContext()).getJavaScriptContextHolder().get() == 0;
 
         if (!isJsDebugging && rncWebView.mCatalystInstance != null) {

apple/RNCWebViewImpl.m

@@ -74,7 +74,7 @@ - (NSString *)stringFromAction:(SEL) action {
       @"toggleUnderline:":   @"underline",
       @"_share:":            @"share",
   };
-    
+
   return map[sel] ?: sel;
 }
 
@@ -86,7 +86,7 @@ - (BOOL)canPerformAction:(SEL)action
           return NO;
       }
   }
-  
+
   if (!self.menuItems) {
       return [super canPerformAction:action withSender:sender];
   }
@@ -143,6 +143,8 @@ @implementation RNCWebViewImpl
   UIStatusBarStyle _savedStatusBarStyle;
 #endif // !TARGET_OS_OSX
   BOOL _savedStatusBarHidden;
+  //Disables the display of prompts during site navigation/loading
+  BOOL _disablePromptDuringLoading;
 
 #if defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 110000 /* __IPHONE_11_0 */
   UIScrollViewContentInsetAdjustmentBehavior _savedContentInsetAdjustmentBehavior;
@@ -177,6 +179,7 @@ - (instancetype)initWithFrame:(CGRect)frame
     _injectedJavaScriptForMainFrameOnly = YES;
     _injectedJavaScriptBeforeContentLoaded = nil;
     _injectedJavaScriptBeforeContentLoadedForMainFrameOnly = YES;
+    _disablePromptDuringLoading = YES;
 
 #if defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 110000 /* __IPHONE_11_0 */
     _savedContentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
@@ -649,6 +652,7 @@ -(void)keyboardDisplacementFix
 - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
   if ([keyPath isEqual:@"estimatedProgress"] && object == self.webView) {
     if(_onLoadingProgress){
+      _disablePromptDuringLoading = YES;
       NSMutableDictionary<NSString *, id> *event = [self baseEvent];
       [event addEntriesFromDictionary:@{@"progress":[NSNumber numberWithDouble:self.webView.estimatedProgress]}];
       _onLoadingProgress(event);
@@ -726,6 +730,7 @@ - (void)userContentController:(WKUserContentController *)userContentController
       NSMutableDictionary<NSString *, id> *event = [self baseEvent];
       [event addEntriesFromDictionary: @{@"navigationType": message.body}];
       _onLoadingFinish(event);
+      _disablePromptDuringLoading = NO;
     }
   } else if ([message.name isEqualToString:MessageHandlerName]) {
     if (_onMessage) {
@@ -1150,44 +1155,48 @@ - (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSStr
  * prompt
  */
 - (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString *))completionHandler{
+  if (!_disablePromptDuringLoading) {
 #if !TARGET_OS_OSX
-  UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"" message:prompt preferredStyle:UIAlertControllerStyleAlert];
-  [alert addTextFieldWithConfigurationHandler:^(UITextField *textField) {
-    textField.text = defaultText;
-  }];
-  UIAlertAction *okAction = [UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
-    completionHandler([[alert.textFields lastObject] text]);
-  }];
-  [alert addAction:okAction];
-  UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
-    completionHandler(nil);
-  }];
-  [alert addAction:cancelAction];
-  alert.preferredAction = okAction;
-  [[self topViewController] presentViewController:alert animated:YES completion:NULL];
-#else
-  NSAlert *alert = [[NSAlert alloc] init];
-  [alert setMessageText:prompt];
-
-  const NSRect RCTSingleTextFieldFrame = NSMakeRect(0.0, 0.0, 275.0, 22.0);
-  NSTextField *textField = [[NSTextField alloc] initWithFrame:RCTSingleTextFieldFrame];
-  textField.cell.scrollable = YES;
-  if (@available(macOS 10.11, *)) {
-    textField.maximumNumberOfLines = 1;
-  }
-  textField.stringValue = defaultText;
-  [alert setAccessoryView:textField];
-
-  [alert addButtonWithTitle:NSLocalizedString(@"OK", @"OK button")];
-  [alert addButtonWithTitle:NSLocalizedString(@"Cancel", @"Cancel button")];
-  [alert beginSheetModalForWindow:[NSApp keyWindow] completionHandler:^(NSModalResponse response) {
-    if (response == NSAlertFirstButtonReturn) {
-      completionHandler([textField stringValue]);
-    } else {
+    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"" message:prompt preferredStyle:UIAlertControllerStyleAlert];
+    [alert addTextFieldWithConfigurationHandler:^(UITextField *textField) {
+      textField.text = defaultText;
+    }];
+    UIAlertAction *okAction = [UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
+      completionHandler([[alert.textFields lastObject] text]);
+    }];
+    [alert addAction:okAction];
+    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
       completionHandler(nil);
+    }];
+    [alert addAction:cancelAction];
+    alert.preferredAction = okAction;
+    [[self topViewController] presentViewController:alert animated:YES completion:NULL];
+#else
+    NSAlert *alert = [[NSAlert alloc] init];
+    [alert setMessageText:prompt];
+
+    const NSRect RCTSingleTextFieldFrame = NSMakeRect(0.0, 0.0, 275.0, 22.0);
+    NSTextField *textField = [[NSTextField alloc] initWithFrame:RCTSingleTextFieldFrame];
+    textField.cell.scrollable = YES;
+    if (@available(macOS 10.11, *)) {
+      textField.maximumNumberOfLines = 1;
     }
-  }];
+    textField.stringValue = defaultText;
+    [alert setAccessoryView:textField];
+
+    [alert addButtonWithTitle:NSLocalizedString(@"OK", @"OK button")];
+    [alert addButtonWithTitle:NSLocalizedString(@"Cancel", @"Cancel button")];
+    [alert beginSheetModalForWindow:[NSApp keyWindow] completionHandler:^(NSModalResponse response) {
+      if (response == NSAlertFirstButtonReturn) {
+        completionHandler([textField stringValue]);
+      } else {
+        completionHandler(nil);
+      }
+    }];
 #endif // !TARGET_OS_OSX
+  } else {
+    completionHandler(nil);
+  }
 }
 
 #if defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 150000 /* iOS 15 */
@@ -1480,6 +1489,7 @@ - (void)webView:(WKWebView *)webView
   }
 
   if (_onLoadingFinish) {
+    _disablePromptDuringLoading = NO;
     _onLoadingFinish([self baseEvent]);
   }
 }