flow-js2-mode

This package adds support for Flow, a static typechecking extension for javascript, to js2-mode, a popular javascript editing mode for Emacs.

It extends the js2-mode parser to understand Flow syntax and exposes it in its AST which you can use to build your own refactoring tools. This understanding of syntax also allows us to add proper syntax highlighting.

This project is heavily WIP at the moment, things might break and change. Please report all the issues, even minor ones so we can polish this as soon as possible.

Usage

Enable flow-js2-mode in the js2-mode buffer.

List of features (incomplete)

• [x] In object literals, {foo: bar} the type is parsed even thought it is not a type. This breaks fontification and semantics of the object literals. I don't see a way yet to distinguish if the foo is a key or a variable.
• [x] import type {Config} from 'types/Config' does not work.
• [x] Typing a destructured object does not work: function send(res, {body, content}: Response)
• [x] Parse function<T> generic constructs.
  • [x] Does not work with multiple generic arguments (separated by commas)
  • [x] Does not work with typed generics such as function <T: number>
• [x] key type specification in objects should work: clients: { [client_id: string]: Client }
• [ ] function types
  • [x] function types with unnamed arguments
  • [ ] function types with named arguments
  • [ ] function types in const/var/let assignments (todo: is this valid flow syntax?)
• [ ] declare module syntax
• [ ] declare class syntax

Related projects

The flow-minor-mode project integrates flow features such as navigation to definition, eldoc support for printing types of expressions at point and similar into Emacs. It is best to use it alongside this package. In fact, it already is a dependency so you will get it automatically when you install this package.

Acknowledgements

The work was started by @antifuchs in this fork and expanded by @Fuco1 in this pull request. It was decided to move this into a separate pacakge as there was no direct relation with rjsx-mode.

Built on top of the powerful features of js2-mode.