# ESLint Configuration Basics — ESLint + Prettier

Source: https://www.geekswithgeeks.com/en/eslint-prettier/eslint-prettier-03

> Understand .eslintrc files and configuration options.

## Configuration anatomy

.eslintrc.json contains env (runtime), extends (base config), rules (customizations), and parserOptions (language settings).

## A complete config

This .eslintrc.json works for JavaScript projects with common rules enabled.

```json
{
  "env": { "browser": true, "node": true, "es2021": true },
  "extends": ["eslint:recommended"],
  "parserOptions": { "ecmaVersion": "latest", "sourceType": "module" },
  "rules": {
    "no-unused-vars": "warn",
    "no-console": "warn",
    "semi": ["error", "always"]
  }
}
```

Output:

```
Configuration loaded successfully
```

## Keep it DRY

Use `extends` to inherit from standard configurations (eslint:recommended, airbnb, google) instead of writing every rule manually.

Quick check

**Quiz:** What does 'extends' do in .eslintrc.json?

- [x] Inherits rule sets from a base configuration.
- [ ] Adds extra files to lint.
- [ ] Enables plugins.

*Answer:* Inherits rule sets from a base configuration.. 'extends' loads a predefined ruleset you can then customize with your own 'rules'.