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Introduction

A cross-platform dart:io that works in browsers, Flutter, and VM.

License

Licensed under the Apache License 2.0.

Much of the source code in this project is from Dart SDK (github.com/dart-lang/sdk/tree/master/sdk/lib/io), which was obtained under the BSD-style license of Dart SDK.

Dart SDK 2.5 breaking changes

• Dart SDK 2.5 (currently in the Dart SDK 'dev' channel) has various breaking changes in dart:io. Consequently this package has breaking changes too.
• If you don't use the 2.5.0-dev-2.0 or later, see dependency constraint recommendations below.

Issues

• Found issues? Report them at the Github issue tracker.
• Have a fix? Create a pull request!

Similar packages

• universal_html (cross-platform dart:html)

Getting started

1.Add a dependency

Dart SDK 2.5.0-dev-2.0 and above

In pubspec.yaml:

dependencies:
  universal_io: '^0.8.2'

Dart SDK 2.4.x

In pubspec.yaml:

dependencies:
  universal_io: '>=0.7.3 <0.8.0'

2. Choose a driver (optional)

VM/Flutter?

• Library "package:universal_io/io.dart" will automatically export dart:io for you.

Browser?

• BrowserIODriver is automatically used when you use Dart2js / devc. This is possible with "conditional imports" feature of Dart.
• The driver implements HttpClient (with restrictions) and a few other features. If you need features such as sockets or unrestricted HTTP connections, choose one of the options below.

Chrome OS App?

• universal_io_driver_chrome_os

3. Use

import 'package:universal_io/io.dart';

void main() async {
  // Use 'dart:io' HttpClient API.
  final httpClient = new HttpClient();
  final request = await httpClient.getUrl(Uri.parse("http://google.com"));
  final response = await request.close();
}

Manual

Default driver behavior

HTTP client

In browser, HTTP client is implemented using dart:html HttpRequest, which uses XmlHttpRequest.

Unlike HTTP client in the standard dart:io, the browser implementation sends HTTP request only after httpRequest.close() has been called.

If a cross-origin request fails, error message contains a detailed description how to fix possible issues like missing cross-origin headers. The error messages look like:

BrowserHttpClient received an error from XMLHttpRequest (which doesn't tell
reason for the error).

HTTP method:   PUT
URL:           http://destination.com
Origin:        http://source.com

Cross-origin request!
CORS 'credentials' mode is disabled (the browser will not send authentication like cookies).
You can enable 'credentials' mode with: request.headers.set('Authorization', "someValue")

Did the server send the following mandatory headers?
  * Access-Control-Allow-Origin: http://source.com
    * OR '*'
  * Access-Control-Allow-Methods: PUT

HttpServer

• Requires sockets.

Platform

• In browser, variables are determined by browser APIs such as navigator.userAgent.
• Elsewhere (e.g. Node.JS), appears like Linux environment.

Files

• Any attempt to use these APIs will throw UnimplementedError.

Sockets

• Any attempt to use these APIs will throw UnimplementedError.

Writing your own driver?

import 'package:universal_io/io.dart';
import 'package:universal_io/driver.dart';
import 'package:universal_io/driver_base.dart';

void main() {
  exampleIODriver.enable();
}

/// Let's change 'Platform' implementation (in browser).
final exampleIODriver = IODriver(
  platformDriver: PlatformDriver(localeName:"en-US"),
).fillMissingFeaturesFrom(defaultIODriver);