Favorite Eslint Rules for Mocha

.eslintrc.js

/**
 * For .ts, install:
 * @typescript-eslint/eslint-plugin
 * @typescript-eslint/parser"
 *
 * For .js, delete these props:
 * parser, plugins, overrides
 */
module.exports = {
  root: true,
  parser: '@typescript-eslint/parser',
  plugins: [
    '@typescript-eslint'
  ],
  extends: [
    'eslint:recommended',
    'semistandard'
  ],
  env: {
    node: true,
    es6: true
  },
  parserOptions: {
    ecmaVersion: 2020,
    sourceType: 'module'
  },
  rules: {
    'array-bracket-newline': [
      'error',
      {
        minItems: 1
      }
    ],
    'array-bracket-spacing': [
      'error',
      'never'
    ],
    'array-element-newline': [
      'error',
      {
        multiline: true,
        minItems: 1
      }
    ],

    'brace-style': [
      'error',
      '1tbs',
      {
        allowSingleLine: true
      }
    ],

    camelcase: [
      'error',
      {
        properties: 'never'
      }
    ],
    'comma-spacing': [
      'error',
      {
        before: false,
        after: true
      }
    ],

    indent: [
      'off',
      2
    ],

    'keyword-spacing': [
      'error'
    ],

    'max-statements-per-line': [
      'error',
      {
        max: 1
      }
    ],

    'no-console': 'error',
    'no-else-return': 'error',
    'no-lonely-if': 'error',
    'no-multiple-empty-lines': [
      2,
      {
        max: 1,
        maxEOF: 1
      }
    ],
    'no-param-reassign': 'error',
    'no-shadow': 'error',
    'no-tabs': 'error',
    'no-trailing-spaces': [
      'error',
      {
        skipBlankLines: false,
        ignoreComments: false
      }
    ],
    'no-unexpected-multiline': 'off',
    'no-unused-vars': [
      'error',
      {
        varsIgnorePattern: '^_'
      }
    ],
    'no-var': 'error',

    'object-curly-newline': [
      'error',
      {
        ObjectExpression: {
          multiline: true,
          minProperties: 1
        },
        ObjectPattern: {
          multiline: true
        },
        ImportDeclaration: {
          multiline: true,
          minProperties: 3
        },
        ExportDeclaration: {
          multiline: true,
          minProperties: 3
        }
      }
    ],
    'object-curly-spacing': [
      'error',
      'always'
    ],
    'object-property-newline': [
      'error',
      {
        allowAllPropertiesOnSameLine: false
      }
    ],

    quotes: [
      'error',
      'single',
      {
        avoidEscape: true
      }
    ],

    'space-before-function-paren': [
      'error',
      {
        named: 'never'
      }
    ],
    'spaced-comment': 'error',

    'unicode-bom': [
      'error',
      'never'
    ],

    yoda: 'error'
  },
  overrides: [
    {
      files: [
        '*.ts'
      ],
      rules: {
        // see https://stackoverflow.com/questions/55280555/typescript-eslint-eslint-plugin-error-route-is-defined-but-never-used-no-un
        '@typescript-eslint/no-unused-vars': 'error',
        'no-unused-vars': 'off',
        'no-undef': 'off',
        // allow overloads
        'no-redeclare': 'off'
      }
    }
  ]
};