.eslintrc

{
  "plugins": [
    "jest"
  ],
  "parserOptions": {
    "ecmaVersion": 2020,
    "sourceType": "module"
  },
  "extends": [
    "eslint:recommended",
    "google",
    "plugin:jest/recommended"
  ],
  "rules": {
    "arrow-parens": [
      "error",
      "as-needed"
    ],
    "comma-dangle": [
      "error",
      {
        "arrays": "only-multiline",
        "objects": "only-multiline",
        "imports": "only-multiline",
        "exports": "only-multiline",
        "functions": "never"
      }
    ],
    "indent": [
      "error",
      4,
      {
        "SwitchCase": 1
      }
    ],
    "max-len": [
      "warn",
      {
        "code": 100
      }
    ],
    "no-invalid-this": "warn",
    "no-param-reassign": [
      "error",
      {
        "props": false
      }
    ],
    "object-curly-spacing": [
      "error",
      "always"
    ],
    "quotes": [
      "error",
      "double"
    ],
    "require-jsdoc": "off",
    "space-before-function-paren": [
      "error",
      {
        "anonymous": "always",
        "named": "never",
        "asyncArrow": "always"
      }
    ]
  },
  "env": {
    "browser": true,
    "es6": true,
    "jest/globals": true
  },
  "overrides": [
    {
      "extends": [
        "plugin:@typescript-eslint/recommended"
      ],
      "files": [
        "*.ts"
      ],
      "parser": "@typescript-eslint/parser",
      "parserOptions": {
        // this seems to be extremely slow
        // without 1.5s, with 22s
        //"project": "./tsconfig.json"
      },
      "plugins": [
        "@typescript-eslint"
      ],
      "rules": {
        "@typescript-eslint/explicit-member-accessibility": "off",
        "@typescript-eslint/explicit-function-return-type": [
          "error",
          {
            "allowExpressions": true
          }
        ],
        "@typescript-eslint/no-parameter-properties": "off",
        "@typescript-eslint/no-explicit-any": "off",
        "@typescript-eslint/no-non-null-assertion": "off"
      }
    }
  ]
}