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Lesson 27 / 27

Summary & Next Steps

Recap the full ESLint and Prettier workflow and plan next steps, from editor setup to CI and shared configs.

What you've mastered

Installation, configuration, integration with editors and CI/CD, custom rules, team setups, and best practices. You're ready to implement ESLint and Prettier in any project.

See the full journey

From setup to CI/CD: the complete ESLint and Prettier workflow.

Figure 25.1 — The full development lifecycle with ESLint and Prettier.

Keep learning and iterating

ESLint and Prettier evolve. Follow their release notes, experiment with new plugins, and refine your configuration as your codebase grows.

Final check

Quick check: What is a good next step in mastering code quality?

  • Stop using linters
  • Use defaults for everything forever
  • Ignore CI
  • Apply ESLint and Prettier to your next project
Answer

Apply ESLint and Prettier to your next project — The best way to master these tools is to use them. Start with a simple setup and refine it over time based on your team's needs.

Final quiz 1 of 8

Final quiz

Quick check: What is ESLint's main job?

  • Compile code
  • Deploy apps
  • Find problems and enforce code-quality rules
  • Minify CSS
Answer

Find problems and enforce code-quality rules — Prettier handles formatting.

Final quiz 2 of 8

Final quiz

Quick check: What does Prettier do?

  • Finds undefined variables
  • Runs tests
  • Bundles files
  • Formats code consistently
Answer

Formats code consistently — It rewrites code to one consistent style.

Final quiz 3 of 8

Final quiz

Quick check: Which file holds ESLint 9's default configuration?

  • eslint.config.js
  • package-lock.json
  • .eslintrc.json
  • .prettierrc
Answer

eslint.config.js — Flat config is the default since ESLint 9.

Final quiz 4 of 8

Final quiz

Quick check: Where should eslint-config-prettier go in your config?

  • First
  • Last
  • It does not matter
  • In .gitignore
Answer

Last — Later entries override earlier formatting rules.

Final quiz 5 of 8

Final quiz

Quick check: What does severity 'error' do?

  • Only warns
  • Disables the rule
  • Fails the lint run
  • Fixes the code
Answer

Fails the lint run — Errors cause a non-zero exit code.

Final quiz 6 of 8

Final quiz

Quick check: What does lint-staged do?

  • Lints the whole repo
  • Stages files automatically
  • Installs Husky
  • Runs linters on staged files only
Answer

Runs linters on staged files only — It keeps pre-commit hooks fast.

Final quiz 7 of 8

Final quiz

Quick check: Why run lint and format checks in CI?

  • To block problem code from merging
  • To make builds slower
  • To delete files
  • To rename branches
Answer

To block problem code from merging — CI enforces rules for everyone.

Final quiz 8 of 8

Final quiz

Quick check: How should a team adopt new rules?

  • Enable all as errors at once
  • Start with warn and tighten gradually
  • Disable lint
  • Skip CI
Answer

Start with warn and tighten gradually — Gradual rollout reduces friction.