Jest is a delightful JavaScript Testing Framework with a focus on simplicity. It works with projects using: Babel, TypeScript, Node, React, Angular, Vue and more!
If you want that, you can use ts-jest instead, or just run the TypeScript compiler tsc separately (or as part of your build process). Via ts-jest ts-jest is a TypeScript preprocessor with source map support for Jest that lets you use Jest to test projects written in TypeScript.
In your test files, Jest puts each of these methods and objects into the global environment. You don't have to require or import anything to use them. However, if you prefer explicit imports, you can do import {describe, expect, test} from '@jest/globals'.
Jest is fast, but due to Jest's test isolation, slow user code often exacerbates performance issues and leads to slow test runs. When tests leave behind open handles like unclosed timers or connections to other services, it can cause Jest to hang or slow down. Jest 30 has gotten better at detecting and reporting these issues, which helps you identify and fix slow or problematic tests more ...
Need help? Jest is worked on by a team of volunteers in their spare time. You can find out ways to talk to community members below.
Jest is a universal testing platform, with the ability to adapt to any JavaScript library or framework. In this section, we'd like to link to community posts and articles about integrating Jest into popular JS libraries.
Jest CLI Options The jest command line runner has a number of useful options. You can run jest --help to view all available options. Many of the options shown below can also be used together to run tests exactly the way you want. Every one of Jest's Configuration options can also be specified through the CLI. Here is a brief overview: Running from the command line Run all tests (default):