ESLint configuration

How to use a configuration:

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

• @cdoublev/eslint-config: to lint (ES6+) files used everywhere (extended by all configurations below)
• @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:

eslint-plugin-compat is used to detect and report usage of unsupported browser interfaces that should be listed in settings.polyfills in the ESLint project configuration file, in order to fix related warning(s).

eslint-plugin-node is used to add rules specific to NodeJS, that was removed in ESLint in v7.

eslint-plugin-react and eslint-plugin-react-hooks are used to add rules specific to react.

eslint-plugin-jest is used to add rules specific to jest.

How rules are selected?

Set up a linter to detect as many errors as possible is often counterproductive: the runtime and unit/integration tests are already detecting errors which can be easily fixed, and an infinite number of error situations might exist and be suitable for adding (an infinite number of) new rules. Therefore selected rules:

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

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