# Is type-check ESM-only? Can you require() it?

> type-check@0.4.0 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

type-check allows you to check the types of JavaScript values at runtime with a Haskell like type syntax.

Last verified Sep 9, 2026 against type-check@0.4.0.

type-check ships CommonJS only. require("type-check") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.8.0. import "type-check" also works because Node.js and Bun can import CommonJS from ES modules, but only the default export is guaranteed; named imports depend on Node's static analysis of the module.

## What to do

1. require("type-check") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.8.0.
2. From ES modules use the default import: import typeCheck from "type-check"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: npm install -D @types/type-check

## Facts

- Latest: 0.4.0 (Apr 3, 2020)
- Module format: CommonJS
- Last CommonJS version: 0.4.0
- TypeScript types: @types/type-check
- Node engines: >= 0.8.0
- Weekly downloads: 101.4M
- License: MIT

## Runtime test results for type-check@0.4.0

Installed and executed on Sep 9, 2026 with require("type-check") from a CommonJS file and import "type-check" from an ES module.

| Runtime | require("type-check") | import "type-check" |
|---|---|---|
| Node.js 18 | works | works |
| Node.js 20 | works | works |
| Node.js 22 | works | works |
| Node.js 24 | works | works |
| Node.js 26 | works | works |
| Bun 1.4.0 | works | works |

## How to import type-check

ES modules:

```js
import typeCheck from "type-check";
```

CommonJS:

```js
const typeCheck = require("type-check");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (6 versions; the newest 6 shown).

| Versions | Format | First published |
|---|---|---|
| 0.1.0 – 0.4.0 | CommonJS | Sep 29, 2013 |

## Frequently asked

**Is type-check ESM-only?**

type-check@0.4.0 is a CommonJS package. type-check ships CommonJS only. require("type-check") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.8.0. import "type-check" also works because Node.js and Bun can import CommonJS from ES modules, but only the default export is guaranteed; named imports depend on Node's static analysis of the module.

**Can I import type-check with ES module syntax?**

Yes. import typeCheck from "type-check" works in Node.js and Bun because they support importing CommonJS modules. Named imports work only when Node.js can statically detect the exports.

**Does type-check work in Bun?**

Yes. import "type-check" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does type-check ship TypeScript types?**

Not bundled. Install the community types with "npm install -D @types/type-check".

## Links

- [type-check on npm](https://www.npmjs.com/package/type-check)
- [Source repository](https://github.com/gkz/type-check)
- [HTML version](https://canirequire.com/package/type-check/)
- [JSON version](https://canirequire.com/package/type-check.json)

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