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

> vary@1.1.2 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

Manipulate the HTTP Vary header

Last verified Sep 9, 2026 against vary@1.1.2.

vary ships CommonJS only. require("vary") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.8. import "vary" 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("vary") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.8.
2. From ES modules use the default import: import vary from "vary"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: npm install -D @types/vary

## Facts

- Latest: 1.1.2 (Sep 24, 2017)
- Module format: CommonJS
- Last CommonJS version: 1.1.2
- TypeScript types: @types/vary
- Node engines: >= 0.8
- Weekly downloads: 100.2M
- License: MIT

## Runtime test results for vary@1.1.2

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

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

ES modules:

```js
import vary from "vary";
```

CommonJS:

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

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (7 versions; the newest 7 shown).

| Versions | Format | First published |
|---|---|---|
| 0.0.0 – 1.1.2 | CommonJS | Jun 4, 2014 |

## Frequently asked

**Is vary ESM-only?**

vary@1.1.2 is a CommonJS package. vary ships CommonJS only. require("vary") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 0.8. import "vary" 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 vary with ES module syntax?**

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

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

**Does vary ship TypeScript types?**

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

## Links

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

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