JavaScript lives in the browser. Therefore you need a way to test it not hypothetically but in reality. That’s where Karma comes in. Karma allows developers to run their JavaScript unit and integration tests from within real browsers. Configuration can be set to utilize any number of browsers like Chrome, Firefox, or in our case, Phantom (a headless browser).
Most other test runners run tests within a hypothetical environment which means once the JavaScript code hits production there may be an issue. With Karma we are able to run our unit tests in an automated fashion using a headless browser and have much higher confidence in the code we are releasing.
Package Name: Karma
Website: http://karma-runner.github.io/