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

> co@4.6.0 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

generator async control flow goodness

Last verified Sep 9, 2026 against co@4.6.0.

co ships CommonJS only. require("co") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.12.0. import "co" 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("co") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.12.0.
2. From ES modules use the default import: import co from "co"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: npm install -D @types/co

## Facts

- Latest: 4.6.0 (Jul 9, 2015)
- Module format: CommonJS
- Last CommonJS version: 4.6.0
- TypeScript types: @types/co
- Node engines: >= 0.12.0
- Weekly downloads: 31.2M
- License: MIT

## Runtime test results for co@4.6.0

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

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

ES modules:

```js
import co from "co";
```

CommonJS:

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

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (34 versions; the newest 34 shown).

| Versions | Format | First published |
|---|---|---|
| 1.0.0 – 4.6.0 | CommonJS | Jun 6, 2013 |

## Frequently asked

**Is co ESM-only?**

co@4.6.0 is a CommonJS package. co ships CommonJS only. require("co") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.12.0. import "co" 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 co with ES module syntax?**

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

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

**Does co ship TypeScript types?**

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

## Links

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

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