# Is istanbul-lib-source-maps ESM-only? Can you require() it?

> istanbul-lib-source-maps@5.0.6 is a CommonJS package. CommonJS — require() works on every Node.js version we test.

Source maps support for istanbul

Last verified Sep 9, 2026 against istanbul-lib-source-maps@5.0.6.

istanbul-lib-source-maps ships CommonJS only. require("istanbul-lib-source-maps") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=10. import "istanbul-lib-source-maps" 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-lib-source-maps") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=10.
2. From ES modules use the default import: import istanbulLibSourceMaps from "istanbul-lib-source-maps"; then destructure. Named imports only work when Node.js can statically detect the exports.
3. TypeScript: npm install -D @types/istanbul-lib-source-maps

## Facts

- Latest: 5.0.6 (Jul 2, 2024)
- Module format: CommonJS
- Last CommonJS version: 5.0.6
- TypeScript types: @types/istanbul-lib-source-maps
- Node engines: >=10
- Weekly downloads: 55.8M
- License: BSD-3-Clause

## Runtime test results for istanbul-lib-source-maps@5.0.6

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

| Runtime | require("istanbul-lib-source-maps") | import "istanbul-lib-source-maps" |
|---|---|---|
| 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-lib-source-maps

ES modules:

```js
import istanbulLibSourceMaps from "istanbul-lib-source-maps";
```

CommonJS:

```js
const istanbulLibSourceMaps = require("istanbul-lib-source-maps");
```

## Module format by version

Derived from the type, main and exports fields of every stable release on npm (27 versions; the newest 27 shown).

| Versions | Format | First published |
|---|---|---|
| 1.0.0 – 5.0.6 | CommonJS | Aug 31, 2016 |

## Frequently asked

**Is istanbul-lib-source-maps ESM-only?**

istanbul-lib-source-maps@5.0.6 is a CommonJS package. istanbul-lib-source-maps ships CommonJS only. require("istanbul-lib-source-maps") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=10. import "istanbul-lib-source-maps" 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-lib-source-maps with ES module syntax?**

Yes. import istanbulLibSourceMaps from "istanbul-lib-source-maps" 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-lib-source-maps work in Bun?**

Yes. import "istanbul-lib-source-maps" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

**Does istanbul-lib-source-maps ship TypeScript types?**

Not bundled. Install the community types with "npm install -D @types/istanbul-lib-source-maps".

## Links

- [istanbul-lib-source-maps on npm](https://www.npmjs.com/package/istanbul-lib-source-maps)
- [Source repository](https://github.com/istanbuljs/istanbuljs)
- [HTML version](https://canirequire.com/package/istanbul-lib-source-maps/)
- [JSON version](https://canirequire.com/package/istanbul-lib-source-maps.json)

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