nixfmt-rs (WebAssembly)

Format Nix code from JavaScript/TypeScript. Same output as nixfmt, byte-for-byte.

npm install nixfmt-rs

Node / bundlers

import { format, version } from "nixfmt-rs";

format("{a=1;}");                          // "{ a = 1; }\n"
format(src, { width: 80, indent: 2, filename: "default.nix" });
version();                                 // "0.1.2"

Parse failures throw a ParseError with message (one line), diagnostic (rendered snippet) and range: [start, end] byte offsets.

Browser (no bundler)

import init, { format } from "nixfmt-rs/web";
await init();
format("{a=1;}");

See https://mic92.github.io/nixfmt-rs/ for a live playground.