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

> gensync@1.0.0-beta.2 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

Allows users to use generators in order to write common functions that can be both sync or async.

Last verified Sep 9, 2026 against gensync@1.0.0-beta.2.

gensync ships CommonJS only. require("gensync") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=6.9.0. import "gensync" 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("gensync") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=6.9.0.
2. From ES modules use the default import: import gensync from "gensync"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: npm install -D @types/gensync

## Facts

- Latest: 1.0.0-beta.2 (Oct 27, 2020)
- Module format: CommonJS
- Last CommonJS version: 0.1.0
- TypeScript types: @types/gensync
- Node engines: >=6.9.0
- Weekly downloads: 127.7M
- License: MIT

## Runtime test results for gensync@1.0.0-beta.2

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

| Runtime | require("gensync") | import "gensync" |
|---|---|---|
| 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 gensync

ES modules:

```js
import gensync from "gensync";
```

CommonJS:

```js
const gensync = require("gensync");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (1 versions; the newest 1 shown).

| Versions | Format | First published |
|---|---|---|
| 0.1.0 | CommonJS | Nov 23, 2015 |

## Frequently asked

**Is gensync ESM-only?**

gensync@1.0.0-beta.2 is a CommonJS package. gensync ships CommonJS only. require("gensync") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=6.9.0. import "gensync" 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 gensync with ES module syntax?**

Yes. import gensync from "gensync" 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 gensync work in Bun?**

Yes. import "gensync" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does gensync ship TypeScript types?**

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

## Links

- [gensync on npm](https://www.npmjs.com/package/gensync)
- [Source repository](https://github.com/loganfsmyth/gensync)
- [HTML version](https://canirequire.com/package/gensync/)
- [JSON version](https://canirequire.com/package/gensync.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.