Does not work on web yet, it stay the screen in blank at launch.

[Garciconx]

import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_translate/flutter_translate.dart';

void main() async {
  var delegate = await LocalizationDelegate.create(
      fallbackLocale: 'en_US',
      supportedLocales: [
        'en_US',
        'es',
      ]);

  runApp(LocalizedApp(delegate, MyApp()));
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    var localizationDelegate = LocalizedApp.of(context).delegate;

    return LocalizationProvider(
      state: LocalizationProvider.of(context).state,
      child: MaterialApp(
        title: 'Flutter Translate Demo',
        localizationsDelegates: [
          GlobalMaterialLocalizations.delegate,
          GlobalWidgetsLocalizations.delegate,
          localizationDelegate
        ],
        supportedLocales: localizationDelegate.supportedLocales,
        //locale: localizationDelegate.currentLocale,
        theme: ThemeData(primarySwatch: Colors.blue),
        home: MyHomePage(),
      ),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    var localizationDelegate = LocalizedApp.of(context).delegate;

    return Scaffold(
      appBar: AppBar(
        title: Text(translate('app_bar.title')),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(translate('language.selected_message', args: {
              'language': translate(
                  'language.name.${localizationDelegate.currentLocale.languageCode}')
            })),
            RaisedButton(
              onPressed: () {
                changeLocale(context, 'en_US');
                print(localizationDelegate.currentLocale.languageCode);
                setState(() {});
              },
              child: Text('english'),
            ),
            RaisedButton(
              onPressed: () {
                changeLocale(context, 'es');

                print(localizationDelegate.currentLocale.languageCode);
                setState(() {});
              },
              child: Text('español'),
            ),
          ],
        ),
      ),
    );
  }
}

[bratan]

Duplicate of https://github.com/bratan/flutter_translate/issues/24