Setup Pre Commit

Setup Pre-Commit Hooks

What This Sets Up

• Husky pre-commit hook
• lint-staged running Biome on all staged files
• Biome config (if missing) — formatter + linter, replaces Prettier + ESLint
• typecheck and test scripts in the pre-commit hook

Steps

1. Detect package manager

Check for package-lock.json (npm), pnpm-lock.yaml (pnpm), yarn.lock (yarn), bun.lockb (bun). Use whichever is present. Default to npm if unclear.

2. Install dependencies

Install as devDependencies:

husky lint-staged @biomejs/biome

3. Initialize Husky

npx husky init

This creates .husky/ dir and adds prepare: "husky" to package.json.

4. Create .husky/pre-commit

Write this file (no shebang needed for Husky v9+):

npx lint-staged
npm run typecheck
npm run test

Adapt: Replace npm with detected package manager. If repo has no typecheck or test script in package.json, omit those lines and tell the user.

5. Create .lintstagedrc

{
  "*": "biome check --write --no-errors-on-unmatched"
}

biome check formats and lints. --write applies safe fixes; --no-errors-on-unmatched stops Biome erroring when a staged file isn't a type it handles (images, etc.).

6. Create biome.json (if missing)

Only create if no Biome config exists (biome.json or biome.jsonc). Use these defaults:

{
  "$schema": "https://biomejs.dev/schemas/2.0.0/schema.json",
  "formatter": {
    "enabled": true,
    "indentStyle": "space",
    "indentWidth": 2,
    "lineWidth": 80
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "double",
      "trailingCommas": "es5",
      "semicolons": "always",
      "arrowParentheses": "always"
    }
  },
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true
    }
  },
  "assist": {
    "actions": {
      "source": {
        "organizeImports": "on"
      }
    }
  }
}

Pin the $schema version to the installed Biome version (check npx biome --version) so the config matches the binary.

7. Verify

• .husky/pre-commit exists and is executable
• .lintstagedrc exists
• prepare script in package.json is "husky"
• biome.json config exists
• Run npx lint-staged to verify it works

8. Commit

Stage all changed/created files and commit with message: Add pre-commit hooks (husky + lint-staged + biome)

This will run through the new pre-commit hooks — a good smoke test that everything works.

Notes

• Husky v9+ doesn't need shebangs in hook files
• biome check does formatting and linting in one pass — no separate Prettier/ESLint steps
• --no-errors-on-unmatched skips files Biome can't handle (images, etc.) instead of failing the commit
• The pre-commit runs lint-staged first (fast, staged-only), then full typecheck and tests