canirequire › ESM-only › mocha
Is mocha ESM-only? Can you require() it?
Classic, reliable, trusted test framework for Node.js and the browser
Last verified Sep 9, 2026 against mocha@12.0.0. JSON
ESM-only ESM-only since 12.0.0 — last CommonJS version is 11.8.0
mocha dropped its CommonJS build in 12.0.0 (August 2026). The last version you can require() on every Node.js version, including 18 and older, is 11.8.0, published Aug 2, 2026.
On Node.js 20.19+, 22.12+ and every newer release, require("mocha") 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.
mocha@12.0.0 declares engines "^20.19.0 || >=22.12.0", so Node.js 18 is outside its supported range regardless of module format.
Does mocha@12.0.0 actually load? Runtime test results
Installed and executed on Sep 9, 2026 with require("mocha") from a CommonJS file and import "mocha" from an ES module.
| Runtime | require("mocha") | import "mocha" |
|---|---|---|
| Node.js 18 | ✗ failsERR_REQUIRE_ESM | ✗ failsERR_REQUIRE_ESM |
| 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 mocha
ES modules (import)
import mocha from "mocha";CommonJS (require)
// Node.js 20.19+ / 22.12+ / newer (package has no top-level await):
const mocha = require("mocha");
// Any Node.js version:
const mocha = await import("mocha");
// Or pin the last CommonJS release:
// npm install mocha@11.8.0Module format by version
Derived from the type, main and exports fields of every stable release on npm (209 versions; the newest 60 shown).
| Versions | Format | First published |
|---|---|---|
| 12.0.0 | ESM-only | Aug 31, 2026 |
| 7.2.0 – 11.8.0 | CommonJS | May 23, 2020 |
Frequently asked
Is mocha ESM-only?
mocha@12.0.0 is ESM-only. mocha dropped its CommonJS build in 12.0.0 (August 2026). The last version you can require() on every Node.js version, including 18 and older, is 11.8.0, published Aug 2, 2026.
Which version of mocha still supports CommonJS / require()?
11.8.0 is the last version of mocha with a CommonJS build. Install it with "npm install mocha@11.8.0". Every version from 12.0.0 on is ESM-only.
How do I use mocha from a CommonJS file?
Use a dynamic import: const mod = await import("mocha"). On Node.js 20.19+, 22.12+ and newer, a plain require("mocha") also works for ESM packages that do not use top-level await. Alternatively pin mocha@11.8.0.
Does mocha work in Bun?
Yes. import "mocha" loaded successfully in Bun 1.4 on Sep 9, 2026.
Does mocha ship TypeScript types?
Not bundled. Install the community types with "npm install -D @types/mocha".
Links
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