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

> js-yaml@5.4.1 ships CommonJS and ESM builds. Dual package — require() works on every Node.js version we test; import works too.

YAML 1.2 parser and serializer

Last verified Sep 9, 2026 against js-yaml@5.4.1.

js-yaml publishes both a CommonJS entry and a native ESM entry (ESM added in 4.0.0). require("js-yaml") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. import "js-yaml" works alongside it.

## What to do

1. Nothing to change. require("js-yaml") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. import * as jsYaml from "js-yaml" works alongside it; use named imports for what the ESM entry exports.
2. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 5.4.1 (Aug 26, 2026)
- Module format: Dual (CommonJS + ESM)
- Last CommonJS version: 5.4.1
- Native ESM since: 4.0.0
- TypeScript types: bundled
- Node engines: not declared
- Weekly downloads: 263.7M
- License: MIT

## Runtime test results for js-yaml@5.4.1

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

| Runtime | require("js-yaml") | import "js-yaml" |
|---|---|---|
| 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 js-yaml

ES modules:

```js
import * as jsYaml from "js-yaml";
```

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

CommonJS:

```js
const jsYaml = require("js-yaml");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (90 versions; the newest 60 shown).

| Versions | Format | First published |
|---|---|---|
| 4.0.0 – 5.4.1 | Dual (CommonJS + ESM) | Jan 3, 2021 |
| 3.2.2 – 3.15.2 | CommonJS | Sep 6, 2014 |

## Frequently asked

**Is js-yaml ESM-only?**

js-yaml@5.4.1 ships CommonJS and ESM builds. js-yaml publishes both a CommonJS entry and a native ESM entry (ESM added in 4.0.0). require("js-yaml") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. import "js-yaml" works alongside it.

**Can I require js-yaml?**

Yes. js-yaml ships a CommonJS entry alongside the native ESM entry. require("js-yaml") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun.

**Does js-yaml work in Bun?**

Yes. import "js-yaml" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does js-yaml ship TypeScript types?**

Yes. js-yaml bundles its own type declarations; no @types package is needed.

## Links

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

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