.eslintrc.json

{
  "parserOptions": {
    "ecmaVersion": 9,
    "sourceType": "module"
  },
  "plugins": ["@typescript-eslint", "prettier"],
  "extends": [
    "eslint:recommended",
    "plugin:prettier/recommended"
  ],
  "env": {
    "browser": true,
    "es6": true
  },
  "rules": {
    "no-console": ["warn", {"allow": ["warn", "error"]}]
  },
  "overrides": [
      {
        "files": ["src/**/*"],
        "parserOptions": {
          "parser": "@typescript-eslint/parser",
          "project": "./tsconfig.json"
        },
        "extends": [
          "plugin:@typescript-eslint/recommended",
          "plugin:@typescript-eslint/recommended-requiring-type-checking"
        ],
        "env": {
          "browser": true
        },
        "rules": {
          "@typescript-eslint/no-non-null-assertion": "off",
          "@typescript-eslint/explicit-member-accessibility": "error",
          "@typescript-eslint/prefer-return-this-type": "error",
          "@typescript-eslint/explicit-function-return-type": ["error", {"allowExpressions": true}]
        }
      }
  ]
}