Install

npm install @wasm-fmt/ruff_fmt

npx jsr add @fmt/ruff-fmt

Usage

Node.js / Deno / Bun / Bundler

import { format } from "@wasm-fmt/ruff_fmt";

const input = `x = {  'a':37,'b':42,

'c':927}

y = 'hello ''world'
z = 'hello '+'world'
a = 'hello {}'.format('world')
class foo  (     object  ):
  def f    (self   ):
    return       37*-+2
  def g(self, x,y=42):
      return y
def f  (   a ) :
  return      37+-+a[42-x :  y**3]`;

const formatted = format(input, "main.py", {
	indent_style: "space",
	indent_width: 4,
	line_width: 88,
	quote_style: "double",
	magic_trailing_comma: "respect",
});
console.log(formatted);

Web

For web environments, you need to initialize WASM module manually:

import init, { format } from "@wasm-fmt/ruff_fmt/web";

await init();

const input = `x = {  'a':37,'b':42,

'c':927}`;

const formatted = format(input, "main.py");
console.log(formatted);

Vite

import init, { format } from "@wasm-fmt/ruff_fmt/vite";

await init();
// ...

Add "@wasm-fmt/ruff_fmt" to optimizeDeps.exclude in your vite config:

{
	"optimizeDeps": {
		"exclude": ["@wasm-fmt/ruff_fmt"]
	}
}

Entry Points

• . - Auto-detects environment (Node.js uses node, Webpack uses bundler, default is ESM)
• ./node - Node.js environment (no init required)
• ./esm - ESM environments like Deno (no init required)
• ./bundler - Bundlers like Webpack (no init required)
• ./web - Web browsers (requires manual init)
• ./vite - Vite bundler (requires manual init)

dprint plugin

Note

dpint plugin is deprecated, please use https://dprint.dev/plugins/ruff instead.

How does it work?

Ruff is an extremely fast Python linter, written in Rust.

This package is a WebAssembly build of Ruff formatter, with a JavaScript wrapper.