By name: eslint description: ESLint JavaScript linter with plugins. Use for code quality.
ESLint
ESLint is the standard linter for JS/TS. v9 (2024/2025) moved to Flat Config (eslint.config.js), a major breaking change that simplifies configuration.
When to Use
- Enforcing Rules:
no-unused-vars,react-hooks/rules-of-hooks. - Code Quality: Catching bugs before they run.
Core Concepts
Flat Config (eslint.config.js)
An array of objects. No more extends string hell.
export default [js.configs.recommended, { rules: { semi: "error" } }];
Plugins
NPM packages that add rules. eslint-plugin-react.
Parsers
@typescript-eslint/parser allows ESLint to understand TS.
Best Practices (2025)
Do:
- Use Flat Config: Use the new format.
- Use
typescript-eslint: The typed linting rules are powerful (e.g.no-floating-promises).
Don't:
- Don't configure formatting rules: Disable all formatting rules (use Prettier or Biome for that). use
eslint-config-prettier.