# Is @emnapi/wasi-threads ESM-only? Can you require() it?

> @emnapi/wasi-threads@2.1.0 is ESM-only. ESM-only since 2.0.0 — last CommonJS version is 1.2.3.

WASI threads proposal implementation in JavaScript

Last verified Sep 9, 2026 against @emnapi/wasi-threads@2.1.0.

@emnapi/wasi-threads dropped its CommonJS build in 2.0.0 (June 2026). The last version with a plain require()-able CommonJS entry is 1.2.3, published Jul 25, 2026.

On Node.js 20.19+, 22.12+ and newer, require("@emnapi/wasi-threads") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26. On Node.js 18, which has no require(esm), require("@emnapi/wasi-threads") fails with ERR_REQUIRE_ESM.

## What to do

1. On Node.js 20.19+, 22.12+ and newer, require("@emnapi/wasi-threads") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26.
2. From a CommonJS file, use a dynamic import inside an async function: const wasiThreads = await import("@emnapi/wasi-threads"). That works on every Node.js version the package supports.
3. If you need a synchronous require() or run Node.js 18: npm install @emnapi/wasi-threads@1.2.3, the last CommonJS release (published Jul 25, 2026).
4. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 2.1.0 (Sep 4, 2026)
- Module format: ESM-only
- Last CommonJS version: 1.2.3
- ESM-only since: 2.0.0 (Jun 8, 2026)
- TypeScript types: bundled
- Node engines: not declared
- Weekly downloads: 66.9M
- License: MIT

## Runtime test results for @emnapi/wasi-threads@2.1.0

Installed and executed on Sep 9, 2026 with require("@emnapi/wasi-threads") from a CommonJS file and import "@emnapi/wasi-threads" from an ES module.

| Runtime | require("@emnapi/wasi-threads") | import "@emnapi/wasi-threads" |
|---|---|---|
| Node.js 18 | fails (ERR_REQUIRE_ESM) | 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 @emnapi/wasi-threads

ES modules:

```js
import * as wasiThreads from "@emnapi/wasi-threads";
```

Namespace import shown because the ESM entry may have no default export; use named imports for what it exports.

CommonJS:

```js
// Node.js 20.19+, 22.12+ and newer (verified):
const wasiThreads = require("@emnapi/wasi-threads");

// Any Node.js version the package supports, from an async function:
async function main() {
  const wasiThreads = await import("@emnapi/wasi-threads");
}

// Or pin the last CommonJS release:
// npm install @emnapi/wasi-threads@1.2.3
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (13 versions; the newest 13 shown).

| Versions | Format | First published |
|---|---|---|
| 2.0.0 – 2.1.0 | ESM-only | Jun 8, 2026 |
| 1.0.0 – 1.2.3 | Dual (CommonJS + ESM) | May 19, 2024 |

## Frequently asked

**Is @emnapi/wasi-threads ESM-only?**

@emnapi/wasi-threads@2.1.0 is ESM-only. @emnapi/wasi-threads dropped its CommonJS build in 2.0.0 (June 2026). The last version with a plain require()-able CommonJS entry is 1.2.3, published Jul 25, 2026.

**Which version of @emnapi/wasi-threads still supports CommonJS / require()?**

1.2.3 is the last version of @emnapi/wasi-threads with a CommonJS build. Install it with "npm install @emnapi/wasi-threads@1.2.3". Every version from 2.0.0 on is ESM-only.

**How do I use @emnapi/wasi-threads from a CommonJS file?**

From a CommonJS file, use a dynamic import inside an async function: const wasiThreads = await import("@emnapi/wasi-threads"). That works on every Node.js version the package supports. On Node.js 20.19+, 22.12+ and newer, require("@emnapi/wasi-threads") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26. Alternatively pin @emnapi/wasi-threads@1.2.3.

**Does @emnapi/wasi-threads work in Bun?**

Yes. import "@emnapi/wasi-threads" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does @emnapi/wasi-threads ship TypeScript types?**

Yes. @emnapi/wasi-threads bundles its own type declarations; no @types package is needed.

## Links

- [@emnapi/wasi-threads on npm](https://www.npmjs.com/package/@emnapi/wasi-threads)
- [Source repository](https://github.com/toyobayashi/emnapi)
- [HTML version](https://canirequire.com/package/@emnapi/wasi-threads/)
- [JSON version](https://canirequire.com/package/@emnapi/wasi-threads.json)

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