ESLint configuration

How to use a configuration:

Append its identifier to the extends property of the ESLint configuration file:

• @cdoublev/eslint-config (extended by all configurations below): to lint (ES6+) files executed anywhere
• @cdoublev/eslint-config/node: to lint files executed in NodeJS
• @cdoublev/eslint-config/browser: to lint files executed in a browser
• @cdoublev/eslint-config/jest: to lint files executed in Jest
• @cdoublev/eslint-config/react: to lint files executed in React

For example, in a React application rendered server side and tested with Jest:

// .eslintrc.js
module.exports = {
  extends: ['@cdoublev/eslint-config'],
  overrides: [
    {
      files: ['__mocks__/**/*.js', '__tests__/**/*.js'],
      extends: ['@cdoublev/eslint-config/node', '@cdoublev/eslint-config/jest'],
    },
    {
      files: ['server/**/*.js'],
      extends: ['@cdoublev/eslint-config/node'],
    },
    {
      files: ['src/**/*.js'],
      extends: ['@cdoublev/eslint-config/react'],
    },
  ],
}

Optional dependencies:

The following dependencies may be required depending on the configuration.

• eslint-plugin-compat is required for @cdoublev/eslint-config/browser and warns against the use of unsupported browser interfaces (these warnings can be muted by listing the corresponding interfaces in settings.polyfills in the ESLint configuration file of the project)
• eslint-plugin-node is required for @cdoublev/eslint-config/node
• eslint-plugin-react and eslint-plugin-react-hooks are required for @cdoublev/eslint-config/react
• eslint-plugin-jest is required for @cdoublev/eslint-config/jest

How rules are selected?

The following conventions apply for selecting rules:

• they must not already be included in eslint:recommended or plugin:[plugin-name]/recommended
• they must be as few as possible to detect errors
• they must be otherwise related to spacing, line breaks, code clarity, and (performance) optimization
• they must not prevent code clarity
• they must be widely accepted by the JS community

Configuring a linter to detect as many errors as possible is often counterproductive: the runtime and tests are already responsible for this.

This document provides some comments about each rule. If a rule exists in this document and is not activated, it will never be.