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Mastering Reactive JavaScript

By : Erich de Souza Oliveira

3.5 (4)

Buy this Book

Mastering Reactive JavaScript

3.5 (4)

By: Erich de Souza Oliveira

Buy this Book

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.

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

What Does Being Reactive Mean?

The reactive paradigm

Why do I need it?

Installation of tools

Your first code using reactive programming

Summary

Reacting for the First Time

The bacon.js observables

Reacting to changes

Reading how an operator works

Transforming events using bacon.js

Summary

A World Full of Changes - Reactive Extensions to the Rescue

RxJS observables

Subscribing to changes (Observer)

RxJS Subjects

RxJS Disposable

RxJS Schedulers

Summary

Transforming Data - Map, Filter, and Reduce

Adding operators to observables

The map() operator

The flatMap() operator

The filter() operator

The reduce() operator

Summary

The World Changes Too Fast - Operators to Deal with Backpressure

What is backpressure?

Common strategies to deal with backpressure

More ways to filter data

Summary

Too Many Sources - Combining Observables

When do I need to combine observables?

Running observables

Concatenating observables

Combining observables

Summary

Something is Wrong - Testing and Dealing with Errors

Dealing with errors

Acting when an error occurs

Summary

More about Operators

The road so far

The fundamentals of RxJS

Going beyond the basics

Other important operators

Summary

Composition

What is a transducer?

Available transducer implementations for JavaScript

The transducers-js API

Using transducers

Using transducers with RxJS

Testing transducers

A performance comparison for JavaScript code using transducers

Summary

A Real-Time Server

The web chat server

Creating the project

The architecture of the server

Implementing the server

Scaling the server

Summary

A Real-Time Client

Installing dependencies

The structure of our client

Building the application for the first time

Connecting to the server application

Using RxJS to manage user input

Connecting user interactions and server communication

Improving interaction with RxJS

Batching changes to the DOM

Testing the application

Summary

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Testing the application

There are several ways that you could create tests for your application; one of the possible options is to create unit tests for your application.

If we decided to create unit tests for our client application, we would need a way to mock the connection with our servers; this would involve creating a new (and slightly complex) build for our tests.

We could also create end to end tests, to test the whole flow of a user. Doing this would probably involve using some external tool to run our tests in the context of a browser and automatize the user input. This would also involve an extra step of running a tool such as Selenium or CasperJS.

There are several books on the different ways you can test a frontend application. Here I'm choosing to implement the simplest solution, which involves creating a page for the test using mocha as explained in Chapter 7, Something is Wrong - Testing and...