What is this?
Flow is a static typechecker for JavaScript: it adds static typing to your code to catch errors early and improve quality. The project goes back to 2014 and is written in Rust.
Flow is a static typechecker for JavaScript: it adds static typing to your code to catch errors early and improve quality. The project goes back to 2014 and is written in Rust.Is it a library I import, or a command-line tool?It's a command-line tool: you run the flow binary against your codebase and it reports type errors. Nothing to import — you just annotate your JavaScript.
It's a command-line tool: you run the flow binary against your codebase and it reports type errors. Nothing to import — you just annotate your JavaScript.How do I get it running?Follow the installation instructions at flow.org, then the usage docs. Prebuilt binaries exist for every supported platform, so a typical setup needs no compiling.
Follow the installation instructions at flow.org, then the usage docs. Prebuilt binaries exist for every supported platform, so a typical setup needs no compiling.Do I need Node or any other runtime installed to run it?Just the binary — no Node, Python or other runtime required. Node, Yarn and Emscripten only come into play if you build the optional flow.js from source.
Just the binary — no Node, Python or other runtime required. Node, Yarn and Emscripten only come into play if you build the optional flow.js from source.Which systems can run it — will an Intel Mac work?macOS (arm64), Linux (x86_64 or arm64) and Windows (x86_64, Windows 10 recommended). Intel Macs aren't in the supported list, so there you'd have to build from source yourself.
macOS (arm64), Linux (x86_64 or arm64) and Windows (x86_64, Windows 10 recommended). Intel Macs aren't in the supported list, so there you'd have to build from source yourself.Can I use it in commercial projects?Yes: Flow is MIT-licensed, so commercial use is fine. The website and docs are separately under Creative Commons Attribution 4.0.
Yes: Flow is MIT-licensed, so commercial use is fine. The website and docs are separately under Creative Commons Attribution 4.0.Can my own tooling parse Flow-typed code?Yes — flow-parser is a compiled-to-JavaScript npm module that produces Flow's syntax tree with annotated types attached. It's meant for tooling authors; most end users never touch it directly.
Yes — flow-parser is a compiled-to-JavaScript npm module that produces Flow's syntax tree with annotated types attached. It's meant for tooling authors; most end users never touch it directly.Is there a JavaScript build of the checker itself?Yes: an optional flow.js build compiles the Rust code with Emscripten into bin/flow.js (needs Node, Yarn, Emscripten and nightly Rust with the wasm32-unknown-emscripten target). A faster but larger local dev build is also documented.
Yes: an optional flow.js build compiles the Rust code with Emscripten into bin/flow.js (needs Node, Yarn, Emscripten and nightly Rust with the wasm32-unknown-emscripten target). A faster but larger local dev build is also documented.Is Flow still actively maintained?It looks that way: the repo was created in October 2014, has about 22k stars, isn't archived, and its CI still runs build-and-test workflows. There's an active community on Discord, IRC and Stack Overflow.
It looks that way: the repo was created in October 2014, has about 22k stars, isn't archived, and its CI still runs build-and-test workflows. There's an active community on Discord, IRC and Stack Overflow.What are similar projects?tools, liteparse, oxc, ast-grep, rector, knip, closure-compiler, difftastic
tools, liteparse, oxc, ast-grep, rector, knip, closure-compiler, difftasticWhich topics is it in?ast, parsing, arm64, code-quality, static-analysis, wasm, web-development, rust, command-line-tool, npm, frontend, tool
ast, parsing, arm64, code-quality, static-analysis, wasm, web-development, rust, command-line-tool, npm, frontend, tool