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

Now that you know the majority of RxJS operators that exist out there, you might wonder if you can create your own custom operators. 

The answer is yes! And it's very easy. 

Every operator is an Observable, which applies to a source Observable. The source Observable might be the original source or an Observable released by the operator before the current operator. With this knowledge, let's first have a look at a problem, and create a custom operator that would help us solve it.

# Publishing and modifying objects 

The following scenario illustrates an object that contains data from a submitted form, flowing through a pipeline to an Observer. The Observer's goal is to append some random string to the user-provided `username`, and make a request to the server. But notice how changing the object's value in the subscribe function leads to a change in the original object. 

That's because the object's reference is passed through the stream, and it is the reference that is modified in the subscribe callback.

Learn how to build a custom RxJS operator from scratch.

The Need for Reactive Programming

RxJS Subjects

RxJS Operators

Testing Observables

Real-World Projects in RxJS

Conclusion

Custom Operators

Publishing and modifying objects