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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. Markdown · 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 with a plain require()-able CommonJS entry is 4.0.0, published Apr 6, 2019; it declares support for Node.js >=8.

On Node.js 20.19+, 22.12+ and newer, require("has-flag") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26. On Node.js 18, which has no require(esm), require("has-flag") fails with ERR_REQUIRE_ESM.

What to do

  1. On Node.js 20.19+, 22.12+ and newer, require("has-flag") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26.
  2. From a CommonJS file, use a dynamic import inside an async function: const hasFlag = await import("has-flag"). That works on every Node.js version the package supports (>=12).
  3. If you need a synchronous require() or run Node.js 18: npm install has-flag@4.0.0, the last CommonJS release (published Apr 6, 2019); it declares Node.js >=8.
  4. TypeScript: no types are available for has-flag; declare the module yourself if you need them.
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 1.4.0✓ works✓ works

How to import has-flag

ES modules (import)

import * as hasFlag from "has-flag";

Namespace import shown because the ESM entry may have no default export; use named imports for what it exports.

CommonJS (require)

// Node.js 20.19+, 22.12+ and newer (verified):
const hasFlag = require("has-flag");

// Any Node.js version the package supports (>=12), from an async function:
async function main() {
  const hasFlag = await import("has-flag");
}

// Or pin the last CommonJS release (declares Node.js >=8):
// 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, corrected where a runtime test of that version contradicted them (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 with a plain require()-able CommonJS entry is 4.0.0, published Apr 6, 2019; it declares support for Node.js >=8.

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

4.0.0 is the last version of has-flag with a CommonJS build; it declares Node.js >=8. 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?

From a CommonJS file, use a dynamic import inside an async function: const hasFlag = await import("has-flag"). That works on every Node.js version the package supports (>=12). On Node.js 20.19+, 22.12+ and newer, require("has-flag") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26. Alternatively pin has-flag@4.0.0 (declares Node.js >=8).

Does has-flag work in Bun?

Yes. import "has-flag" loaded successfully in Bun 1.4.0 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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