.eslintrc.json

{
  "root": true,

  "parserOptions": {
    "sourceType": "module"
  },

  "env": {
    "browser": false,
    "es2017": true,
    "node": true
  },

  "extends": ["eslint:recommended", "plugin:prettier/recommended"],

  "overrides": [
    {
      "files": ["*.ts"],

      "parser": "@typescript-eslint/parser",
      "parserOptions": {
        "project": "tsconfig.json",
        "sourceType": "module"
      },
      "env": {
        "browser": false,
        "es2020": true,
        "node": true
      },

      "extends": [
        "eslint:recommended",
        "plugin:@typescript-eslint/eslint-recommended",
        "plugin:@typescript-eslint/recommended",
        "plugin:@typescript-eslint/recommended-requiring-type-checking",
        "plugin:prettier/recommended"
      ],
      "rules": {
        "@typescript-eslint/no-use-before-define": [
          "error",
          { "functions": false }
        ]
      }
    }
  ]
}