.eslintrc.json

{
    "$schema": "https://json.schemastore.org/eslintrc",
    "root": true,
    "env": {
        "browser": true,
        "node": true,
        "es6": true
    },
    "parser": "@typescript-eslint/parser",
    "parserOptions": {
        "project": "./tsconfig.json"
    },
    "extends": [
        "eslint:recommended",
        "plugin:@typescript-eslint/eslint-recommended",
        "plugin:@typescript-eslint/recommended",
        "plugin:@typescript-eslint/recommended-requiring-type-checking",
        "plugin:mithril/recommended",
        "plugin:cypress/recommended",
        "plugin:prettier/recommended"
    ],
    "plugins": [
        "prettier",
        "@typescript-eslint"
    ],
    "rules": {
        // Disable the rule for all files to allow for mixed js/ts.
        // https://github.com/typescript-eslint/typescript-eslint/blob/v3.9.1/packages/eslint-plugin/docs/rules/explicit-module-boundary-types.md
        "@typescript-eslint/explicit-module-boundary-types": "off",
        // Don't allow relative imports. VSCode will also use absolute imports by default.
        "no-restricted-imports": [
            "error",
            {
                "patterns": [
                    "./*",
                    "../*",
                    "!./*.css", // Allow relative imports for CSS.
                    "!../*.css", // Allow relative imports for CSS.
                    "!./*.scss", // Allow relative imports for SCSS.
                    "!../*.scss" // Allow relative imports for SCSS.
                ]
            }
        ]
    },
    "overrides": [
        {
            // Enable the rule specifically for TypeScript files to allow for mixed js/ts.
            "files": [
                "*.ts",
                "*.tsx"
            ],
            "rules": {
                "@typescript-eslint/explicit-module-boundary-types": [
                    "error"
                ]
            }
        }
    ]
}