Nowadays, JavaScript has become the de facto programming language to build and empower frontend/web applications. We can use JavaScript to develop simple or complex applications. However, applications in production are often vulnerable to bugs caused by design inconsistencies, logical implementation errors, and similar issues. For this reason, it is usually difficult to predict how applications will behave in real-time environments, which leads to unexpected behavior, non-availability of applications, or outages for short or long durations. This generates lack of confidence and dissatisfaction among application users. Also, high cost is often associated with fixing the production bugs. Therefore, there is a need to develop applications that are of a high quality and that offer high availability.

Jasmine plays a vital role to establish effective development process by applying efficient testing processes. Jasmine is an excellent framework for testing JavaScript code both in browser and on the server side. We well use version 2.0.1 of Jasmine in this book. In this chapter, we will cover how tests can be written for JavaScript code using the Jasmine framework. You will also learn how various Jasmine matchers play a pivotal role for writing the tests.