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Is has-flag ESM-only? Can you require() it?

Check if argv has a specific flag

Last verified Sep 9, 2026 against has-flag@5.0.1. JSON

ESM-only ESM-only since 5.0.0 — last CommonJS version is 4.0.0

has-flag dropped its CommonJS build in 5.0.0 (April 2021). The last version you can require() on every Node.js version, including 18 and older, is 4.0.0, published Apr 6, 2019.

On Node.js 20.19+, 22.12+ and every newer release, require("has-flag") works anyway: Node can load synchronous ES modules through require(). Verified on Node 20, 22, 24, 26. Node.js 18 and older still fail with ERR_REQUIRE_ESM.

Latest
5.0.1 (Jul 19, 2021)
Module format
ESM-only
Last CommonJS version
4.0.0
ESM-only since
5.0.0 (Apr 16, 2021)
TypeScript types
None
Node engines
>=12
Weekly downloads
166.9M
License
MIT

Does has-flag@5.0.1 actually load? Runtime test results

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

Runtimerequire("has-flag")import "has-flag"
Node.js 18✗ failsERR_REQUIRE_ESM✓ 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 has-flag

ES modules (import)

import hasFlag from "has-flag";

CommonJS (require)

// Node.js 20.19+ / 22.12+ / newer (package has no top-level await):
const hasFlag = require("has-flag");

// Any Node.js version:
const hasFlag = await import("has-flag");

// Or pin the last CommonJS release:
// npm install has-flag@4.0.0

Module format by version

Derived from the type, main and exports fields of every stable release on npm (6 versions; the newest 6 shown).

VersionsFormatFirst published
5.0.0 – 5.0.1ESM-onlyApr 16, 2021
1.0.0 – 4.0.0CommonJSJul 7, 2015

Frequently asked

Is has-flag ESM-only?

has-flag@5.0.1 is ESM-only. has-flag dropped its CommonJS build in 5.0.0 (April 2021). The last version you can require() on every Node.js version, including 18 and older, is 4.0.0, published Apr 6, 2019.

Which version of has-flag still supports CommonJS / require()?

4.0.0 is the last version of has-flag with a CommonJS build. Install it with "npm install has-flag@4.0.0". Every version from 5.0.0 on is ESM-only.

How do I use has-flag from a CommonJS file?

Use a dynamic import: const mod = await import("has-flag"). On Node.js 20.19+, 22.12+ and newer, a plain require("has-flag") also works for ESM packages that do not use top-level await. Alternatively pin has-flag@4.0.0.

Does has-flag work in Bun?

Yes. import "has-flag" loaded successfully in Bun 1.4 on Sep 9, 2026.

Does has-flag ship TypeScript types?

No. has-flag ships no type declarations and there is no @types package for it.

Links

Other esm-only packages

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