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[flutter_tools] Keep web loading bar visible until app starts - #192483
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The blue loading indicator on Flutter Web was previously removed when receiving the `dart-app-ready` DOM event. However, DWDS dispatches `dart-app-ready` immediately when the injected debug client connects to the debug service protocol, which occurs while Frontend Server is still compiling the application. This change replaces the `dart-app-ready` listener with an explicit `window._removeFlutterLoader` function that is invoked directly before executing the application entrypoint in both `generateMainModule` and `generateDDCLibraryBundleMainModule`.
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This pull request replaces the 'dart-app-ready' event listener in the web bootstrap script with a global window._removeFlutterLoader function to handle the removal of the loading indicator and stylesheet, and updates the main module generation and tests accordingly. Feedback suggests clearing the global window._removeFlutterLoader reference inside the function itself to prevent potential memory leaks by allowing the DOM elements and closure scope to be garbage collected.
# Conflicts: # packages/flutter_tools/lib/src/web/bootstrap.dart # packages/flutter_tools/test/general.shard/web/bootstrap_test.dart
This was referenced Sep 10, 2026
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The blue loading indicator on Flutter Web was previously removed when receiving the
dart-app-readyDOM event. However, DWDS dispatchesdart-app-readyimmediately when the injected debug client connects to the debug service protocol, which occurs while Frontend Server is still compiling the application.This change:
dart-app-readylistener with an explicitwindow._removeFlutterLoaderfunction that is invoked directly before executing the application entrypoint in bothgenerateMainModuleandgenerateDDCLibraryBundleMainModule.window._removeFlutterLoaderupon execution to allow the DOM elements and closure scope to be garbage collected.translateXandscaleXwithwill-change: transform;andtransform-origin: left;) instead of layout properties (left/width), preventing the animation from freezing when the browser evaluates large JavaScript bundles.Pre-launch Checklist
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