# Is unist-util-is ESM-only? Can you require() it?

> unist-util-is@6.0.1 is ESM-only. ESM-only since 5.0.0 — last CommonJS version is 4.1.0.

unist utility to check if a node passes a test

Last verified Sep 9, 2026 against unist-util-is@6.0.1.

unist-util-is dropped its CommonJS build in 5.0.0 (April 2021). The last version with a plain require()-able CommonJS entry is 4.1.0, published Mar 7, 2021.

On Node.js 20.19+, 22.12+ and newer, require("unist-util-is") 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("unist-util-is") fails with ERR_REQUIRE_ESM.

## What to do

1. On Node.js 20.19+, 22.12+ and newer, require("unist-util-is") 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 unistUtilIs = await import("unist-util-is"). That works on every Node.js version the package supports.
3. If you need a synchronous require() or run Node.js 18: npm install unist-util-is@4.1.0, the last CommonJS release (published Mar 7, 2021).
4. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 6.0.1 (Oct 16, 2025)
- Module format: ESM-only
- Last CommonJS version: 4.1.0
- ESM-only since: 5.0.0 (Apr 19, 2021)
- TypeScript types: bundled
- Node engines: not declared
- Weekly downloads: 57.4M
- License: MIT

## Runtime test results for unist-util-is@6.0.1

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

| Runtime | require("unist-util-is") | import "unist-util-is" |
|---|---|---|
| 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 unist-util-is

ES modules:

```js
import * as unistUtilIs from "unist-util-is";
```

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 unistUtilIs = require("unist-util-is");

// Any Node.js version the package supports, from an async function:
async function main() {
  const unistUtilIs = await import("unist-util-is");
}

// Or pin the last CommonJS release:
// npm install unist-util-is@4.1.0
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (20 versions; the newest 20 shown).

| Versions | Format | First published |
|---|---|---|
| 5.0.0 – 6.0.1 | ESM-only | Apr 19, 2021 |
| 1.0.0 – 4.1.0 | CommonJS | Sep 2, 2015 |

## Frequently asked

**Is unist-util-is ESM-only?**

unist-util-is@6.0.1 is ESM-only. unist-util-is dropped its CommonJS build in 5.0.0 (April 2021). The last version with a plain require()-able CommonJS entry is 4.1.0, published Mar 7, 2021.

**Which version of unist-util-is still supports CommonJS / require()?**

4.1.0 is the last version of unist-util-is with a CommonJS build. Install it with "npm install unist-util-is@4.1.0". Every version from 5.0.0 on is ESM-only.

**How do I use unist-util-is from a CommonJS file?**

From a CommonJS file, use a dynamic import inside an async function: const unistUtilIs = await import("unist-util-is"). That works on every Node.js version the package supports. On Node.js 20.19+, 22.12+ and newer, require("unist-util-is") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26. Alternatively pin unist-util-is@4.1.0.

**Does unist-util-is work in Bun?**

Yes. import "unist-util-is" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does unist-util-is ship TypeScript types?**

Yes. unist-util-is bundles its own type declarations; no @types package is needed.

## Links

- [unist-util-is on npm](https://www.npmjs.com/package/unist-util-is)
- [Source repository](https://github.com/syntax-tree/unist-util-is)
- [HTML version](https://canirequire.com/package/unist-util-is/)
- [JSON version](https://canirequire.com/package/unist-util-is.json)

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