Jest "Cannot use import statement outside a module" (ESM)

By Kaveh Alemi·Latchkey

Jest hit raw ESM import syntax it never compiled to CommonJS. Usually an ESM-only dependency is skipped by the default transformIgnorePatterns, or no transform is configured for your own files.

What this error means

A suite fails to parse with "SyntaxError: Cannot use import statement outside a module," pointing at a file inside node_modules (an ESM-only package) or at your own untransformed TS/JSX source.

/app/node_modules/nanoid/index.js:1
export { nanoid } from './index.browser.js';
^^^^^^

SyntaxError: Cannot use import statement outside a module

Common causes

ESM-only dependency not transformed

Jest ignores node_modules by default. An ESM-only package (nanoid, uuid, query-string) is loaded as-is and its import breaks under CommonJS.

No transform for your own source

Without babel-jest or ts-jest configured, Jest cannot compile your own import/TSX either and throws the same SyntaxError on source files.

How to fix it

Allow-list the ESM package for transform

Carve the ESM dependency out of transformIgnorePatterns so Jest compiles it instead of skipping it.

// jest.config.js
module.exports = {
  transformIgnorePatterns: ['/node_modules/(?!(nanoid|uuid|query-string)/)'],
};

Configure a transform for your code

1. Add babel-jest with @babel/preset-env (plus preset-typescript/preset-react as needed).
2. Or use ts-jest for TypeScript projects.
3. Confirm the transform glob covers every source extension you import.

How to prevent it

• Update transformIgnorePatterns as ESM-only deps are added.
• Standardize on babel-jest or ts-jest for the whole repo.
• Consider Vitest for ESM-first projects to avoid transform config.

Frequently asked questions

Related guides

References

• GitHub Actions documentation