Book Image

Mastering Reactive JavaScript

By : Erich de Souza Oliveira
Book Image

Mastering Reactive JavaScript

By: Erich de Souza Oliveira

Overview of this book

If you’re struggling to handle a large amount of data and don’t know how to improve your code readability, then reactive programming is the right solution for you. It lets you describe how your code behaves when changes happen and makes it easier to deal with real-time data. This book will teach you what reactive programming is, and how you can use it to write better applications. The book starts with the basics of reactive programming, what Reactive Extensions is, and how can you use it in JavaScript along with some reactive code using Bacon. Next, you’ll discover what an Observable and an Observer are and when to use them.You'll also find out how you can query data through operators, and how to use schedulers to react to changes. Moving on, you’ll explore the RxJs API, be introduced to the problem of data traffic (backpressure), and see how you can mitigate it. You’ll also learn about other important operators that can help improve your code readability, and you’ll see how to use transducers to compose operators. At the end of the book, you’ll get hands-on experience of using RxJs, and will create a real-time web chat using RxJs on the client and server, providing you with the complete package to master RxJs.
Table of Contents (11 chapters)

Chapter 4. Transforming Data - Map, Filter, and Reduce

In the previous chapter, we started discussing the use of RxJS in our programs. To start using it, we compared Observables in Reactive Extensions with EventStreams and Properties in bacon.js. Then we looked at some of the most common sources of data we can use to create Observables, as follows:

  • Arrays
  • Range
  • Interval
  • Promises and callbacks
  • DOM events
  • Any arbitrary source

After this initial overview of the RxJS API on how to create Observables, we learned how to subscribe to them so we are able to take action whenever new data is made available in the Observable. Subscribing to an Observable means being able to not only react to new incoming data, but also to take some action when an error occurs or an Observable finishes. To do this, we learned how to use the subscribe()method, using functions or by creating an Observer.

We also learned how to use Subjects. Subjects allow us to create new Observables and keep pushing data to them.

RxJS gives us...