Flutter Universal Platform Check - That Works on Web too

platform_is.dart

import 'universal_platform_web.dart'
    if (dart.library.io) 'universal_platform_vm.dart';

/// A universal platform checker.
///
/// Can be used to check active physical Flutter platform on all platforms.
///
/// To check what host platform the app is running on use:
///
/// * PlatformIs.android
/// * PlatformIs.iOS
/// * PlatformIs.macOS
/// * PlatformIs.windows
/// * PlatformIs.linux
/// * PlatformIs.fuchsia
///
/// To check the device type use:
///
/// * PlatformIs.mobile  (Android or iOS)
/// * PlatformIs.desktop (Windows, macOS or Linux)
///
/// Currently Fuchsia is not considered mobile nor desktop, even if it
/// might be so in the future.
///
/// To check if the Flutter application is running on Web you can use:
///
/// * PlatformIs.web
///
/// Alternatively the Flutter foundation compile time constant kIsWeb also
/// works well for that.
///
/// The platform checks are supported independently on web. You can use
/// PlatformIs windows, iOS, macOS, Android and Linux to check what the host
/// platform is when you are running a Flutter Web application.
///
/// Checking if we are running on a Fuchsia host in a Web browser, is not yet fully
/// supported. If running in a Web browser on Fuchsia, PlatformIs.web will be true, but
/// PlatformIs.fuchsia will be false. Future versions, when Fuchsia is released, 
/// may fix this.
class PlatformIs {
  PlatformIs._();
  static bool get web => UniversalPlatform.web;
  static bool get macOS => UniversalPlatform.macOS;
  static bool get windows => UniversalPlatform.windows;
  static bool get linux => UniversalPlatform.linux;
  static bool get android => UniversalPlatform.android;
  static bool get iOS => UniversalPlatform.iOS;
  static bool get fuchsia => UniversalPlatform.fuchsia;
  static bool get mobile => PlatformIs.iOS || PlatformIs.android;
  static bool get desktop =>
      PlatformIs.macOS || PlatformIs.windows || PlatformIs.linux;
}

universal_platform_vm.dart

import 'dart:io';
// NOTE:
// Never import this library directly in the application. The PlatformIs
// class and library uses conditional imports to only import this file on
// VM platform builds.

// UniversalPlatform for Flutter VM builds.
//
// We are using Dart VM builds, so we use dart:io Platform to
// get the current platform.
class UniversalPlatform {
  UniversalPlatform._();
  static bool get web => false;
  static bool get macOS => Platform.isMacOS;
  static bool get windows => Platform.isWindows;
  static bool get linux => Platform.isLinux;
  static bool get android => Platform.isAndroid;
  static bool get iOS => Platform.isIOS;
  static bool get fuchsia => Platform.isFuchsia;
}

universal_platform_web.dart

// ignore: avoid_web_libraries_in_flutter
import 'dart:html' as html;

// NOTE:
// Never import this library directly in the application. The PlatformIs
// class and library uses conditional imports to only import this file on
// Web platform builds.

final html.Navigator _nav = html.window.navigator;

// UniversalPlatform for Flutter WEB build.
//
// We can use dart:html Navigator to get the current platform.
//
// This function is borrowed, with minor modifications, from GetX utils library with MIT license.
// Credits for it belong to its author Jonny Borges https://github.com/jonataslaw
// https://github.com/jonataslaw/getx/blob/master/lib/get_utils/src/platform/platform_web.dart
//
class UniversalPlatform {
  UniversalPlatform._();
  static bool get web => true;
  static bool get macOS => _nav.appVersion.contains('Mac OS') && !iOS;
  static bool get windows => _nav.appVersion.contains('Win');
  static bool get linux =>
      (_nav.appVersion.contains('Linux') || _nav.appVersion.contains('x11')) &&
      !android;
  // Source: https://developer.chrome.com/multidevice/user-agent
  static bool get android => _nav.appVersion.contains('Android ');
  static bool get iOS {
    // maxTouchPoints is needed to separate iPad iOS13 vs new MacOS
    return _hasMatch(_nav.platform, '/iPad|iPhone|iPod/') ||
        (_nav.platform == 'MacIntel' && _nav.maxTouchPoints! > 1);
  }

  // Theoretically we could be in a Web browser on Fuchsia too, but
  // we have no info on how to get that info yet, so we return false.
  static bool get fuchsia => false;
}

bool _hasMatch(String? value, String pattern) {
  // ignore: avoid_bool_literals_in_conditional_expressions
  return (value == null) ? false : RegExp(pattern).hasMatch(value);
}

A useful helper to check which Platform a Flutter Application is running on

If you are making a multiplatform app you might sometimes need to check if the app is running on Web or what platform on the VM.
The built in Platform in dart.io will throw if imported on web, so you cannot use it on Web at all. You have to use conditional import wrappers to avoid the error.

What if you want to know what the host platform is when you are running on web? The dart:html that can help you with that.

These three simple files shows one way of doing it, you do not really need a package for this thing. 😃

---

MIT License

Copyright (c) 2021 Mike Rydstrom

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