setup-pre-commit

name	setup-pre-commit
description	Set up Husky pre-commit hooks with lint-staged (Prettier), type checking, and tests in the current repo. Use when user wants to add pre-commit hooks, set up Husky, configure lint-staged, or add commit-time formatting/typechecking/testing.
tags	["mattpocock","setup-pre-commit","testing"]

Setup Pre-Commit Hooks

What This Sets Up

• Husky pre-commit hook
• lint-staged running Prettier on all staged files
• Prettier config (if missing)
• 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 prettier

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

{
  "*": "prettier --ignore-unknown --write"
}

6. Create .prettierrc (if missing)

Only create if no Prettier config exists. Use these defaults:

{
  "useTabs": false,
  "tabWidth": 2,
  "printWidth": 80,
  "singleQuote": false,
  "trailingComma": "es5",
  "semi": true,
  "arrowParens": "always"
}

7. Verify

• .husky/pre-commit exists and is executable
• .lintstagedrc exists
• prepare script in package.json is "husky"
• prettier 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 + prettier)

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
• prettier --ignore-unknown skips files Prettier can't parse (images, etc.)
• The pre-commit runs lint-staged first (fast, staged-only), then full typecheck and tests