Learn about RxJS to write efficient asynchronous code. Explore subjects, operators, and observables. Gain insights into creating projects like a reactive local database and handling DOM events.

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RxJS (Reactive Extensions for JavaScript) is a very powerful library for web development which allows you to easily write asynchronous or call-back code.

In this course, you will explore the latest version of RxJS in detail, focusing on how to apply the reactive paradigm to solve your day-to-day tasks. You will learn all the major components of this library including: subjects, operators, and how to test observables.

In the last section of this course, you will get hands-on with this library to create your own project. Throughout this project, you’ll learn about building a centralized loading indicator, how to handle DOM events, how to build a reactive local database, and more.

By the end of this course, you will have a great new skill to add to your resume, and a cool new project for your portfolio.

Building Reactive Applications with RxJS

As in every software development paradigm, testing is the most important aspect to maintain a bug-free, scalable codebase. Even reactive applications need their tests to ensure that the data stream is running in the right direction. But, how is testing performed in this case?

According to what we have learned so far, a subscriber will subscribe to an Observable and will receive some values. In that case, we can perform tests on the values that are expected to be received by the subscriber. However, that approach, as we will see in the next lesson, has a few downsides, mostly related to testing Observables that emit multiple values over different time intervals.

Those downsides will be overcome by using Marble Tests. They allow us to provide a virtual time to the Observables that we are testing, in order to test asynchronous data streams in a synchronous way.


With that being said, let's jump right in.

Learn about different approaches to test reactive streams.

The Need for Reactive Programming

RxJS Subjects

RxJS Operators

Testing Observables

Real-World Projects in RxJS

Conclusion

Introduction to Testing in RxJS