# Is istanbul-instrumenter-loader ESM-only? Can you require() it?

> istanbul-instrumenter-loader@3.0.1 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

Istanbul instrumenter loader for webpack

Last verified Sep 9, 2026 against istanbul-instrumenter-loader@3.0.1.

istanbul-instrumenter-loader ships CommonJS only. require("istanbul-instrumenter-loader") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 4.8 < 5.0.0 || >= 5.10. import "istanbul-instrumenter-loader" 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("istanbul-instrumenter-loader") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 4.8 < 5.0.0 || >= 5.10.
2. From ES modules use the default import: import istanbulInstrumenterLoader from "istanbul-instrumenter-loader"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: no types are available for istanbul-instrumenter-loader; declare the module yourself if you need them.

## Facts

- Latest: 3.0.1 (Mar 28, 2018)
- Module format: CommonJS
- Last CommonJS version: 3.0.1
- TypeScript types: none
- Node engines: >= 4.8 < 5.0.0 || >= 5.10
- Weekly downloads: 152K
- License: MIT

## Runtime test results for istanbul-instrumenter-loader@3.0.1

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

| Runtime | require("istanbul-instrumenter-loader") | import "istanbul-instrumenter-loader" |
|---|---|---|
| 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 istanbul-instrumenter-loader

ES modules:

```js
import istanbulInstrumenterLoader from "istanbul-instrumenter-loader";
```

CommonJS:

```js
const istanbulInstrumenterLoader = require("istanbul-instrumenter-loader");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (11 versions; the newest 11 shown).

| Versions | Format | First published |
|---|---|---|
| 0.1.0 – 3.0.1 | CommonJS | Sep 25, 2014 |

## Frequently asked

**Is istanbul-instrumenter-loader ESM-only?**

istanbul-instrumenter-loader@3.0.1 is a CommonJS package. istanbul-instrumenter-loader ships CommonJS only. require("istanbul-instrumenter-loader") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >= 4.8 < 5.0.0 || >= 5.10. import "istanbul-instrumenter-loader" 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 istanbul-instrumenter-loader with ES module syntax?**

Yes. import istanbulInstrumenterLoader from "istanbul-instrumenter-loader" 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 istanbul-instrumenter-loader work in Bun?**

Yes. import "istanbul-instrumenter-loader" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does istanbul-instrumenter-loader ship TypeScript types?**

No. istanbul-instrumenter-loader ships no type declarations and there is no @types package for it.

## Links

- [istanbul-instrumenter-loader on npm](https://www.npmjs.com/package/istanbul-instrumenter-loader)
- [Source repository](https://github.com/webpack-contrib/istanbul-instrumenter-loader)
- [HTML version](https://canirequire.com/package/istanbul-instrumenter-loader/)
- [JSON version](https://canirequire.com/package/istanbul-instrumenter-loader.json)

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