Purpose

Use packages/prettier-compare/ to inspect any differences between Biome and Prettier formatting (including IR output) before shipping formatter changes.

Prerequisites

• Run every command from the repository root so relative paths resolve correctly.

• Use bun (the CLI is a Bun script) and ensure dependencies have been installed.

• Always pass --rebuild so the Biome WASM bundle matches your current Rust changes.

Common workflows

Snippets passed as CLI args:

bun packages/prettier-compare/bin/prettier-compare.js --rebuild 'const x={a:1,b:2}'

Force a language (useful when the tool cannot infer it from a filename):

bun packages/prettier-compare/bin/prettier-compare.js --rebuild -l ts 'const x: number = 1'

Compare files on disk:

bun packages/prettier-compare/bin/prettier-compare.js --rebuild -f src/example.tsx

Read from stdin (great for piping editor selections):

echo 'const x = 1' | bun packages/prettier-compare/bin/prettier-compare.js --rebuild -l js

Tips

• Use -l/--language when formatting code without an extension so both formatters pick the correct parser.

• Use -f/--file for large samples or snapshot tests so you can iterate directly on project fixtures.

• Reference packages/prettier-compare/README.md for deeper CLI details; mirror any updates here, keeping the hard requirement that commands include --rebuild .

• Use single quotes for code snippets passed as CLI arguments to avoid shell interpretation issues.

• "\n" does not get escaped into a newline when passed as a CLI argument. You should write a literal newline or use a file instead.