Can you run Dart directly or do you have to transpile to JS?
Alex Mills

Yes, and you do that most of the time when developing, actually. Dart VM ( is part of the SDK. It’s very fast. It enables things like server-side Dart, dart-sass (the only official SASS implementation, although that one also transpiles to JavaScript for when you need to run it through npm), Dartium and the Flutter development experience (with sub-second hot reload on iOS and Android).

You use the dart2js compiler only for production. It generates heavily optimized JavaScript, using whole program knowledge, so it’s slow (medium apps take seconds).

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