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

> reflect-metadata@0.2.2 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

Polyfill for Metadata Reflection API

Last verified Sep 9, 2026 against reflect-metadata@0.2.2.

reflect-metadata ships CommonJS only. require("reflect-metadata") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. import "reflect-metadata" 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("reflect-metadata") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun.
2. From ES modules use the default import: import reflectMetadata from "reflect-metadata"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: types are bundled; install nothing extra.

## Facts

- Latest: 0.2.2 (Mar 29, 2024)
- Module format: CommonJS
- Last CommonJS version: 0.2.2
- TypeScript types: bundled
- Node engines: not declared
- Weekly downloads: 28.5M
- License: Apache-2.0

## Runtime test results for reflect-metadata@0.2.2

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

| Runtime | require("reflect-metadata") | import "reflect-metadata" |
|---|---|---|
| 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 reflect-metadata

ES modules:

```js
import reflectMetadata from "reflect-metadata";
```

CommonJS:

```js
const reflectMetadata = require("reflect-metadata");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (19 versions; the newest 19 shown).

| Versions | Format | First published |
|---|---|---|
| 0.0.2 – 0.2.2 | CommonJS | Apr 14, 2015 |

## Frequently asked

**Is reflect-metadata ESM-only?**

reflect-metadata@0.2.2 is a CommonJS package. reflect-metadata ships CommonJS only. require("reflect-metadata") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. import "reflect-metadata" 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 reflect-metadata with ES module syntax?**

Yes. import reflectMetadata from "reflect-metadata" 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 reflect-metadata work in Bun?**

Yes. import "reflect-metadata" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does reflect-metadata ship TypeScript types?**

Yes. reflect-metadata bundles its own type declarations; no @types package is needed.

## Links

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

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