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

YAML 1.2 parser and serializer

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

Dual (CommonJS + ESM) Dual package — require() works on every Node.js version we test; import works too

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.
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

Does js-yaml@5.4.1 actually load? Runtime test results

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

Runtimerequire("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 (import)

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 (require)

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

Module format by version

Derived from the type, main and exports fields of every stable release on npm, corrected where a runtime test of that version contradicted them (90 versions; the newest 60 shown).

VersionsFormatFirst published
4.0.0 – 5.4.1Dual (CommonJS + ESM)Jan 3, 2021
3.2.2 – 3.15.2CommonJSSep 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

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