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)

What is backpressure?


When using functional reactive programming, we model our problems using streams of data or events (called observables), which can be transformed (using operators) and eventually will cause some effect (through an observer). Now imagine that we have an observable which emits data faster than our observer can process; this will lead to a problem called backpressure.

This problem can also happen when we want to keep an observable running at a certain pace. Imagine that you want to log in to the console all the tweets from a certain hashtag, but you want to log at most one each for a few seconds to make sure the user can read the tweets. This also can lead to backpressure if the hashtags have more tweets per second than a human is capable of reading.

Using RxJS, we have two possible strategies to deal with this problem.

We can discard some data. You might not be interested in all the movements of your user mouse or all the tweets from a certain hashtag. You are only interested...