canirequire

canirequire › CommonJS › is-weakmap

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

Is this value a JS WeakMap? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

Last verified Sep 9, 2026 against is-weakmap@2.0.2. JSON

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

is-weakmap ships CommonJS only. require("is-weakmap") works everywhere. import "is-weakmap" 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.

Latest
2.0.2 (Mar 8, 2024)
Module format
CommonJS
Last CommonJS version
2.0.2
TypeScript types
Bundled
Node engines
>= 0.4
Weekly downloads
56.6M
License
MIT

Does is-weakmap@2.0.2 actually load? Runtime test results

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

Runtimerequire("is-weakmap")import "is-weakmap"
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✓ works✓ works

How to import is-weakmap

ES modules (import)

import isWeakmap from "is-weakmap";

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 isWeakmap = require("is-weakmap");

Module format by version

Derived from the type, main and exports fields of every stable release on npm (5 versions; the newest 5 shown).

VersionsFormatFirst published
1.0.0 – 2.0.2CommonJSFeb 18, 2015

Frequently asked

Is is-weakmap ESM-only?

is-weakmap@2.0.2 is a CommonJS package. is-weakmap ships CommonJS only. require("is-weakmap") works everywhere. import "is-weakmap" 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-weakmap with ES module syntax?

Yes. import isWeakmap from "is-weakmap" 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-weakmap work in Bun?

Yes. import "is-weakmap" loaded successfully in Bun 1.4 on Sep 9, 2026.

Does is-weakmap ship TypeScript types?

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

Links

Other commonjs packages

Similar popularity