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Getting Started

Install the plugin:

npm install --save-dev eslint-plugin-typefest typescript

Enable one preset in your Flat Config:

import typefest from "eslint-plugin-typefest";

export default [
    typefest.configs.recommended,
];

recommended does not require type information.

If you want the same baseline plus type-aware helper rules, use typefest.configs["recommended-type-checked"].

Alternative: manual scoped setupโ€‹

If you prefer to apply plugin rules inside your own file-scoped config object, spread the preset rules manually.

import tsParser from "@typescript-eslint/parser";
import typefest from "eslint-plugin-typefest";

export default [
    {
        files: ["**/*.{ts,tsx,mts,cts}"],
        languageOptions: {
            parser: tsParser,
            parserOptions: {
                ecmaVersion: "latest",
                // Enable only when using a type-aware preset.
                // projectService: true,
                sourceType: "module",
            },
        },
        plugins: {
            typefest,
        },
        rules: {
            ...typefest.configs.recommended.rules,
        },
    },
];

Use this pattern when you only extend rules and want full control over parser setup per scope.

  1. Start with recommended (or minimal if you want low initial noise).
  2. Fix violations in small batches.
  3. Move to recommended-type-checked when you are ready for typed rules.
  4. Move to strict once your baseline is stable.
  5. Use all when you want every stable rule.
  6. Use experimental only when you want report-only candidate rules under active evaluation.

Need a subset instead of a full preset?โ€‹

  • ๐Ÿ’  typefest.configs["type-fest/types"]
  • โœด๏ธ typefest.configs["ts-extras/type-guards"]

See the Presets section in this sidebar for details and examples.