This page has information on migrating your Dart 1.x web app to Dart 2. These changes are necessary because of the following:

• Tooling changes:
  • Chrome replaces Dartium and content-shell.
  • A new build system replaces pub build, pub serve, pub transformers.
• Dart 2 language and library changes.

Tools

The development environment for web apps is different in Dart 2 from Dart 1.x. Here are the highlights:

Dart 1.x	Dart 2
Dartium, content shell	Chrome and the webdev tool
pub build	webdev build
pub serve	webdev serve
pub run angular_test	dart run build_runner test -- -p chrome
pub transformers	build package transformers. See: Transforming code

Code

To migrate to Dart 2, you’ll need to edit your web app’s project files:

• pubspec.yaml. See details below.
• HTML files with <script src="foo.dart"...> elements, such as web/index.html. See details below.
• Dart code, due to changes in the Dart language and libraries.

For complete examples of migrating apps, look at the files changed between the 4.x and master branches of the following apps:

• Quickstart
• Tour of Heroes, part 5

Pubspec

Make these changes to your pubspec.yaml file:

• Add new dev_dependencies:
  • build_runner:
  • build_test: , if you are running tests
  • build_web_compilers:
• Drop dev_dependencies:
  • browser
  • dart_to_js_script_rewriter
• Upgrade to test version 0.12.30 or later; it runs Chrome tests headless by default.
• Drop all transformers:
  • angular
  • dart_to_js_script_rewriter
  • test/pub_serve

For example, look at the differences in the Quickstart example’s pubspec with these changes applied.

HTML with script elements

The most common example of a file with <script> elements is web/index.html. You’ll need to make these changes:

• Drop <script defer src="packages/browser/dart.js"></script>
• Replace <script defer src="foo.dart" type="application/dart"></script> by
  <script defer src="foo.dart.js"></script>

For example, look at the differences in the Quickstart example’s web/index.html page with these changes applied.

Additional resources

The Dart 2 migration guide has information about changes in Dart 2, and how to migrate your code from Dart 1.x.