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)

Combining observables


We already learned how we can create an observable containing all data from the other observables, but we can also use some other operators to combine this data or choose between them instead of just propagating everything.

Using the forkJoin() operator

This operator lets you run multiple observables in parallel and propagates the last elements of each one, so this operator is perfect for implementing flow control for promises or callback operations in JavaScript, as we already discussed in this chapter.

This operator has the following signature:

Rx.Observable.forkJoin(observables); 

This is a class() method instead of an instance() method, and it receives an arbitrary number of arguments and the last is optional:

  • observables: An arbitrary number of observable sequences to be executed

Note

It can also accept a last argument to concatenate the items of the produced array, but this is not a common use case as you can easily do it using the map() operator over the array.

The forkJoin...