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

> which-builtin-type@1.2.1 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

What is the type of this builtin JS value?

Last verified Sep 9, 2026 against which-builtin-type@1.2.1.

which-builtin-type ships CommonJS only. require("which-builtin-type") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.4. import "which-builtin-type" 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("which-builtin-type") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.4.
2. From ES modules use the default import: import whichBuiltinType from "which-builtin-type"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 1.2.1 (Dec 13, 2024)
- Module format: CommonJS
- Last CommonJS version: 1.2.1
- TypeScript types: bundled
- Node engines: >= 0.4
- Weekly downloads: 68.7M
- License: MIT

## Runtime test results for which-builtin-type@1.2.1

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

| Runtime | require("which-builtin-type") | import "which-builtin-type" |
|---|---|---|
| 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 which-builtin-type

ES modules:

```js
import whichBuiltinType from "which-builtin-type";
```

CommonJS:

```js
const whichBuiltinType = require("which-builtin-type");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (9 versions; the newest 9 shown).

| Versions | Format | First published |
|---|---|---|
| 1.0.0 – 1.2.1 | CommonJS | Jan 25, 2020 |

## Frequently asked

**Is which-builtin-type ESM-only?**

which-builtin-type@1.2.1 is a CommonJS package. which-builtin-type ships CommonJS only. require("which-builtin-type") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.4. import "which-builtin-type" 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 which-builtin-type with ES module syntax?**

Yes. import whichBuiltinType from "which-builtin-type" 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 which-builtin-type work in Bun?**

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

**Does which-builtin-type ship TypeScript types?**

Yes. which-builtin-type bundles its own type declarations; no @types package is needed.

## Links

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

---

For scripts and AI agents: any package is at https://canirequire.com/package/<name>/index.md (Markdown) or https://canirequire.com/package/<name>.json (JSON); the site index is https://canirequire.com/llms.txt. Fetch the URL directly; no search needed.