Jasmine provides you with the testing primitives such as describe(), it(), expect(value).toEqual(other): http://facebook.github.io/jest/docs/api.html#globally-inject...

Jest adds multiple layers on-top:

- A mock library (also called stubs) in order to create fake functions and assert that they are called as you want: http://facebook.github.io/jest/docs/mock-functions.html#cont...

- A way to provide an alternate implementation for dependencies using require(): http://facebook.github.io/jest/docs/common-js-testing.html#c...

- It inspects the shape of your dependencies and return a mocked version of them: http://facebook.github.io/jest/docs/automatic-mocking.html#c...

- Finally, it works in node instead of the browser and uses jsdom to let you test code related to the DOM. (It also runs tests in parallel)