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Is is-buffer ESM-only? Can you require() it?

Determine if an object is a Buffer

Last verified Sep 9, 2026 against is-buffer@2.0.5. Markdown · JSON

CommonJS CommonJS — require() works on every Node.js version we test

is-buffer ships CommonJS only. require("is-buffer") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=4. import "is-buffer" 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("is-buffer") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=4.
  2. From ES modules use the default import: import isBuffer from "is-buffer"; then destructure. Named imports only work when Node.js can statically detect the exports.
  3. TypeScript: npm install -D @types/is-buffer
Latest
2.0.5 (Nov 3, 2020)
Module format
CommonJS
Last CommonJS version
2.0.5
TypeScript types
@types/is-buffer
Node engines
>=4
Weekly downloads
36.0M
License
MIT

Does is-buffer@2.0.5 actually load? Runtime test results

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

Runtimerequire("is-buffer")import "is-buffer"
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 is-buffer

ES modules (import)

import isBuffer from "is-buffer";

Named imports from a CommonJS package only work when Node.js can statically detect them. If a named import fails, use the default import and destructure.

CommonJS (require)

const isBuffer = require("is-buffer");

Module format by version

Derived from the type, main and exports fields of every stable release on npm, corrected where a runtime test of that version contradicted them (16 versions; the newest 16 shown).

VersionsFormatFirst published
1.0.0 – 2.0.5CommonJSOct 31, 2014

Frequently asked

Is is-buffer ESM-only?

is-buffer@2.0.5 is a CommonJS package. is-buffer ships CommonJS only. require("is-buffer") works on every Node.js version we test (18, 20, 22, 24 and 26) and in Bun. The package declares Node.js >=4. import "is-buffer" 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 is-buffer with ES module syntax?

Yes. import isBuffer from "is-buffer" 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 is-buffer work in Bun?

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

Does is-buffer ship TypeScript types?

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

Links

Other commonjs packages

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