ECMAScript Modules

With the warnings out of the way, this is how you activate ESM support in your tests.

1. Execute node with --experimental-vm-modules, e.g. node --experimental-vm-modules node_modules/jest/bin/jest.js or etc..

   On Windows, you can use cross-env to be able to set environment variables.

   If you use Yarn, you can use yarn node --experimental-vm-modules $(yarn bin jest). This command will also work if you use .

2. If you want to treat other file extensions (such as .jsx or .ts) as ESM, please use the extensionsToTreatAsEsm option.

Most of the differences are explained in , but in addition to the things mentioned there, Jest injects a special variable into all executed files - the jest object. To access this object in ESM, you need to import it from the @jest/globals module. To access this object in ESM, you need to import it from the @jest/globals module or use .

Please note that we currently don’t support jest.mock in a clean way in ESM, but that is something we intend to add proper support for in the future. Follow for updates. Follow this issue for updates.