🏳️Jest · 🃏 Delightful JavaScript Testing

Website faviconjestjs.io

[Skip to main content](#__docusaurus_skipToContent_fallback)

Support Ukraine 🇺🇦 [Help Provide Humanitarian Aid to Ukraine](https://opensource.facebook.com/support-ukraine).

[

Follow @jestjs\_](https://twitter.com/intent/follow?screen_name=jestjs_&region=follow_link)

JEST

JEST

RUNSRUNSRUNSRUNS

JEST

JEST

RUNSRUNSRUNSRUNS

JEST

JEST

RUNSRUNSRUNSRUNS

JEST

JEST

RUNSRUNSRUNSRUNS

JEST

JEST

RUNSRUNSRUNSRUNS

[Get Started](/docs/getting-started)[Docs](/docs/getting-started)[Config](/docs/configuration)[Get help](/help)

Jest is a delightful JavaScript Testing Framework with a focus on simplicity.

It works with projects using: [Babel](https://babeljs.io/), [TypeScript](https://www.typescriptlang.org/), [Node](https://nodejs.org/), [React](https://reactjs.org), [Angular](https://angular.io), [Vue](https://vuejs.org) and more!

Zero config

-----------------

Jest aims to work out of the box, config free, on most JavaScript projects.

Snapshots

---------------

Make tests which keep track of large objects with ease. Snapshots live either alongside your tests, or embedded inline.

Isolated

--------------

Tests are parallelized by running them in their own processes to maximize performance.

Great api

---------------

From `it` to `expect` - Jest has the entire toolkit in one place. Well documented, well maintained, well good.

Fast and safe

-------------------

By ensuring your tests have unique global state, Jest can reliably run tests in parallel. To make things quick, Jest runs previously failed tests first and re-organizes runs based on how long test files take.

Code coverage

-------------------

Generate code coverage by adding the flag [`--coverage`](/docs/cli#--coverageboolean). No additional setup needed. Jest can collect code coverage information from entire projects, including untested files.

Easy Mocking

------------------

Jest uses a custom resolver for imports in your tests, making it simple to mock any object outside of your test’s scope. You can use mocked imports with the rich [Mock Functions](/docs/mock-functions) API to spy on function calls with readable test syntax.

Great Exceptions

----------------------

Tests fail—when they do, Jest provides rich context why. Here are some examples:

toBetoBeCloseTotoEqualtoStrictEqualtoHavePropertytoMatchSnapshottoThrowError

Philosophy

----------

Jest is a JavaScript testing framework designed to ensure correctness of any JavaScript codebase. It allows you to write tests with an approachable, familiar and feature-rich API that gives you results quickly.

Jest is well-documented, requires little configuration and can be extended to match your requirements.

Jest makes testing delightful.

\- Jest Core Team

\- Jest Core Team

Docs and talks

--------------

The Jest core team and contributors regularly speak about [Jest and Delightful JavaScript Testing](https://www.youtube.com/watch?v=cAKYQpTC7MA). Check out our talk about [Building High-Quality JavaScript Tools](https://www.youtube.com/watch?v=PvabBs_utr8) at jsconf.eu 2017 and our talk about [Jest as a Platform](https://www.youtube.com/watch?v=NtjyeojAOBs) at ReactiveConf 2017.

Open Collective

---------------

Jest uses Open Collective to support developers contributing to Jest.

### Featured Sponsors

[](https://www.principal.com/about-us "$7950 by Principal Financial Group")[](https://www.airbnb.com/ "$7720 by Airbnb")[](https://nx.dev "$3600 by Nx (by Nrwl)")[](https://datadoghq.com "$1300 by Datadog")

[Join 25+ donors](https://opencollective.com/jest#section-contributors) who sponsor Jest for $3 or more per month on [opencollective.com](https://opencollective.com/jest#section-contributors).

Who uses Jest?

--------------

A lot of people! With [300+ million](https://www.npmjs.com/package/jest) downloads in the last month, and used on over [11,000,000](https://github.com/jestjs/jest/network/dependents) public repos on GitHub.

Jest is used extensively at these companies:

[](https://www.facebook.com)[](https://www.twitter.com)[](http://www.nytimes.com/)[](https://www.spotify.com)[](https://www.airbnb.com/)[](https://www.instagram.com/)