.eslintrc.json

{
  "parser": "babel-eslint",
  "env": {
    "browser": true,
    "es6": true,
    "node": true,
    "jest": true
  },
  "extends": ["eslint:recommended"],
  "parserOptions": {
    "ecmaVersion": 2018,
    "sourceType": "module"
  },
  "rules": {
    "strict": ["error", "never"]
  }
}