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)

Transforming events using bacon.js

One important thing when learning functional reactive programming is how you can transform the events emitted by an observable. This way, you can use successive function calls to create new objects from the original input. This also improves the reuse of your code; every transformation of an observable creates a new observable, and each observable can have several listeners subscribed to it.

Before applying any transformations to our observables, let's implement an observable to generate and print the current date. To do this, let's use the Bacon.interval() method. So, the following code will emit an empty object every second:

var eventSource = Bacon 


Remember, Bacon.interval() emits an empty object every x milliseconds, where x is the argument passed to the function–in our example, every 1000 milliseconds, which is the same as every second.

Now we can just subscribe a function to print the current date to the console. We can do this...