Dart 2 migration guide for web apps

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.

See also: Angular Migration Guide v4 to v5

Tools

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

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 migrated apps, compare the 4.x and master branchesof any one of the angular-examples apps, such as these:

• 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, here is a diff ofangular-examples/quickstart/pubspec.yamlwith 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>

Here is a diff ofangular-examples/quickstart/web/index.htmlwith these changes applied.

Additional resources

• Dart 2 Updates:Information about changes in Dart 2, and how to migrate your code from Dart 1.x.
• Changelog:Lists changes made to this site’s documentation and examples.