bootstrapEngine function

Future<void> bootstrapEngine(
  1. {VoidCallback? registerPlugins,
  2. VoidCallback? runApp}

Bootstraps the Flutter Web engine and app.

If the app uses plugins, then the registerPlugins callback can be provided to register those plugins. This is done typically by calling registerPlugins from the auto-generated web_plugin_registrant.dart file.

The runApp callback is invoked to run the app after the engine is fully initialized.

For more information, see what the flutter_tools does in the entrypoint that it generates around the app's main method:

By default, engine initialization and app startup occur immediately and back to back. They can be programmatically controlled by setting FlutterLoader.didCreateEngineInitializer. For more information, see how flutter.js does it:


Future<void> bootstrapEngine({
  ui.VoidCallback? registerPlugins,
  ui.VoidCallback? runApp,
}) async {
  // Create the object that knows how to bootstrap an app from JS and Dart.
  final AppBootstrap bootstrap = AppBootstrap(
    initializeEngine: ([JsFlutterConfiguration? configuration]) async {
      await initializeEngineServices(jsConfiguration: configuration);
    }, runApp: () async {
      if (registerPlugins != null) {
      await initializeEngineUi();
      if (runApp != null) {

  final FlutterLoader? loader = flutter?.loader;
  if (loader == null || loader.isAutoStart) {
    // The user does not want control of the app, bootstrap immediately.
    domWindow.console.debug('Flutter Web Bootstrap: Auto.');
    await bootstrap.autoStart();
  } else {
    // Yield control of the bootstrap procedure to the user.
    domWindow.console.debug('Flutter Web Bootstrap: Programmatic.');