.eslintrc.json

{
  "env": {
    "es6": true
  },
  
  "plugins": ["fp"],
  
  "extends": ["next/core-web-vitals", "plugin:fp/recommended"],
  
  "rules": {
    "fp/no-arguments": "error",
    "fp/no-class": "error",
    "fp/no-delete": "error",
    "fp/no-events": "error",
    "fp/no-get-set": "error",
    "fp/no-let": "error",
    "fp/no-loops": "error",
    "fp/no-mutating-assign": "error",
    "fp/no-mutating-methods": "error",
    "fp/no-mutation": "error",
    "fp/no-nil": "off",
    "fp/no-proxy": "error",
    "fp/no-rest-parameters": "error",
    "fp/no-this": "error",
    "fp/no-throw": "error",
    "fp/no-unused-expression": "off",
    "fp/no-valueof-field": "error",
    "no-var": "error",

    // additional recommendations from Ilya Suzdalnitsky 
    // https://betterprogramming.pub/js-reliable-fdea261012ee
    "max-lines": ["warn", 200],
    "max-lines-per-function": ["off", 20],
    "complexity": ["warn", 5],
    "max-nested-callbacks": ["warn", 2],
    "max-depth": ["warn", 3],
    "no-param-reassign": "warn",
    "max-params": ["warn", 2]
  }
}