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)

Adding operators to observables


In Chapter 2, Reacting for the First Time, we used operators using bacon.js. They let us transform our data before it reaches the subscribers of the given Observable. The operators in RxJS work similar to the ones in bacon.js; some even have the same name. They are just methods called from Observable objects, as you can see in the following example:

Rx.Observable 
  .just('Hello ') 
  .map((msg)=>msg+'World') 
  .subscribe((msg)=> console.log(msg)); 

In this example, we created an Observable, which emits only one string, and called the map() operator over this Observable and subscribed to it to show the result in the console:

    Hello World

Note

If you can't recall the map() operator from Chapter 2, Reacting for the First Time, don't worry! We will see more of it and what it does later in this chapter.

Every time you call an operator over an observable, it returns a new observable with the transformation applied. This way, we can chain multiples operators...