Collectives™ on Stack Overflow

Find centralized, trusted content and collaborate around the technologies you use most.

Teams

Q&A for work

Connect and share knowledge within a single location that is structured and easy to search.

I have just started learning jest testing and created a sample application to get familiar with jest testing. However, I am getting following error...

Language.js

const calculateTip = (total, percentage) => {
    return total + ((percentage / 100) * total) + 1;
export {
    calculateTip,
package.json
    "dependencies": {
        "express": "^4.18.2"
    "type": "module",
    "main": "src/app.js",
    "scripts": {
        "start": "node src/app.js",
        "test": "cls && env-cmd -f ./envs/test.env jest --watchAll"
    "devDependencies": {
        "env-cmd": "^10.1.0",
        "jest": "^29.2.2",
        "supertest": "^6.3.1"
I have tried googling for the solution but no luck so far.
Node.js supports esm syntax only from v16, but jest doesn't support it yet.
Therefore, you have 2 choices:
Don't use the esm syntax (import / export)
Add jest-babel with it's config to transpile (convert) esm syntax to cjs one.
                Thank you @felixmosh, Although this worked, there are so many depreciation warnings while installing the packages. I had to delete the node_modules directory and install the package before running the npm install command.
– Mr.Singh
                Nov 3, 2022 at 6:49
Jest now ships with experimental support for ECMAScript Modules (ESM):
https://jestjs.io/docs/ecmascript-modules
The simplest way forward is to update your test script to execute node with --experimental-vm-modules e.g.
node --experimental-vm-modules node_modules/jest/bin/jest.js
or to add an environment variable to the test script
NODE_OPTIONS=--experimental-vm-modules npx jest
See the link above for more details.
                The solution is correct. Just to add, in Windows to set NODE_OPTIONS env you may want to use this package: github.com/kentcdodds/cross-env
– D_S_toowhite
                Jun 1 at 6:25
You can fix it by installing jest-babel and then creating babel.config.cjs in your root directory and pasting the following into it:
//babel.config.cjs
module.exports = {
  presets: [
      '@babel/preset-env',
        targets: {
          node: 'current',
//package.json
"type": "module"
//tsconfig.json
"target": "esnext", 
"module": "commonjs", 
        
Thanks for contributing an answer to Stack Overflow!
Please be sure to answer the question. Provide details and share your research!
But avoid …
Asking for help, clarification, or responding to other answers.
Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.