Getting the typed syntax tree from dart2js or dart-analyzer

I'd like to derive exactly that subset of the sources of a dart comiler (dart2js or dartdevc or other) or of a dart analyser that can 1. transform a string of dart code (or better a list of strings each representing a compilation unit) into a typed syntax tree, 2. be translated into js, 3. be run in the browser. Is there a marked subset that fulfills these requirements, which is it, and how can I find it, in general.

Accomplishing #1 is fairly simple using package:analyzer, which is the same static analyzer used to provide IDE hinting and autocomplete, etc. The Dart Team is currently working on unifying their compiler frontends behind on main API, but for now, analyzer should definitely take care of most of what you need.

Here's an example of getting a syntax tree and running analysis on it: https://github.com/thosakwe/analyzer_examples/blob/master/analyze_a_file/analyze_a_file.dart

As for #2, you'll likely have to fork the dart-lang/sdk repo and make your own adjustments to dart2js. It's not published as a standalone package. Otherwise, you can write your own compiler, which is probably not going be fun.

3. I suppose you'd have to figure out how to get #2 up and running, but hypothetically, if you could compile a JavaScript source, you could just eval it after compilation.

To answer your final question, no, AFAIK, there is no subset of dart2js available that lets you create your own Dart-to-JavaScript compiler.