.eslintrc.js

module.exports = {
  "env": {
    "es6": true,
    "node": true,
    "jest": true
  },
  "extends": "eslint:recommended",
  "parser": "babel-eslint",
  "parserOptions": {
    "ecmaVersion": 2018,
    "sourceType": "module"
  },
  "plugins": ["jest"],
  "rules": {
    "indent": [
      "error",
      2
    ],
    "linebreak-style": [
      "error",
      "unix"
    ],
    "quotes": [
      "error",
      "single"
    ],
    "semi": [
      "error",
      "never"
    ],
    "space-before-function-paren": [
      "error",
      "always"
    ],
    "object-curly-spacing": [
      "error",
      "always"
    ],
    "array-bracket-spacing": [
      "error",
      "always"
    ],
    "key-spacing": [
      "error",
      {"afterColon": true}
    ],
    "comma-spacing": [
      "error",
      {"after": true}
    ],
    "comma-dangle": [
      "error",
      "never"
    ],
    "quote-props": [
      "error",
      "as-needed"
    ],
    "prefer-object-spread": [
      "error"
    ],
    "prefer-const": [
      "error",
    ],
    "prefer-arrow-callback": [
      "error",
    ],
    "prefer-template": [
      "error",
    ],

    // Jest lint
    "jest/no-disabled-tests": "warn",
    "jest/no-focused-tests": "error",
    "jest/no-identical-title": "error",
    "jest/prefer-to-have-length": "warn",
    "jest/valid-expect": "error"
  }
}