How to Run a Prettier Format Check in GitHub Actions

Formatting debates waste reviews; prettier --check makes the formatter the arbiter and fails the build when code drifts.

Run prettier --check . so unformatted files exit non-zero, turning the PR check red until the author runs prettier --write.

Steps

• Install dependencies with npm ci.
• Run prettier --check . against the repository (respecting .prettierignore).
• Let the non-zero exit fail the job so unformatted code is blocked.

Workflow

name: Prettier
on: [pull_request]
jobs:
  prettier:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: npm
      - run: npm ci
      - run: npx prettier --check .

Notes

• Keep a .prettierignore so generated files do not trip the check.
• On Latchkey managed runners format checks run cheaper and self-heal if a runner drops.

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