.eslintrc.js

/*
module.exports = {
    extends: [
        'eslint:recommended',
        'plugin:import/errors',
        'plugin:import/warnings',
        'plugin:react/recommended', // 'React' is defined but never used
    ],
    env: {
        es6: true, // 'Promise' is not defined.
        browser: true, // 'document' is not defined
        commonjs: true, // 'require' is not defined
        node: true, // 'process' is not defined
    },
    settings: {
        'react': {
            version: '16.9', // Warning: React version not specified in eslint-plugin-react settings
        },
        'import/resolver': {
            webpack: {
                env: 'development',
            },
        },
    },
    // if using ES proposals is essential:
    parser: 'babel-eslint', // Unexpected token
    parserOptions: {
        ecmaVersion: 2018, // Parsing error: Unexpected token ...
        sourceType: 'module', // Parsing error: The keyword 'import' is reserved
    },
    rules: {
        // Added rules (fixable -> warn)
        'quotes': ['warn', 'single'],
        'object-curly-spacing': ['warn', 'always'],
        'semi': ['warn', 'never'],
        'eol-last': ['warn', 'always'],
        'linebreak-style': ['warn', 'unix'],
        'no-trailing-spaces': ['warn'],
        'arrow-parens': ['warn', 'as-needed'],
        'react/jsx-closing-bracket-location': ['warn', 'tag-aligned'],
        'react/self-closing-comp': ['warn'],
        'react/jsx-tag-spacing': ['warn'],
        'quote-props': ['warn', 'consistent-as-needed'],
        'indent': ['warn', 2],
        'space-before-function-paren': ['warn', {
            anonymous:  'always',
            named:      'never',
            asyncArrow: 'always' }],
        'comma-dangle': ['warn', {
            arrays:    'always-multiline',
            objects:   'always-multiline',
            imports:   'always-multiline',
            exports:   'always-multiline',
            functions: 'always-multiline' }],

        // Added rules (non-fixable -> error)
        'no-duplicate-imports': ['error'],
        'no-implicit-globals': ['error'],
        'no-restricted-globals': ['error',
            'closed', 'frames', 'history', 'length', 'location', 'name', 'navigator', 'opener', 'parent', 'screen', 'status', 'top'],
        'no-unused-vars': ['error', {
            argsIgnorePattern: '^_' }],

        // Disabled rules
        'no-console': ['off'],
        'react/prop-types': ['off'],
    },
}
*/