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)

Dealing with errors

Detecting and treating errors in asynchronous code are hard tasks. For synchronous code, we can use the famous try/catch/finally block. Treating an exception with this block is easy, as can be seen in the following code:

  throw new Error('An error occurred'); 
  console.log('Treating the error'); 
  console.log('Last computation'); 

Unfortunately, we can't use the try/catch/finally on asynchronous code. In JavaScript we run asynchronous code most of the time, so the language and the community elaborated a couple of strategies.

Initially, the only strategy we had available to deal with asynchronous code was the use of callback functions, so most libraries in JavaScript added the onSuccess() and onError() methods, which accepted a callback function to be executed when an error happened or when data is available. Different frameworks used different methods for doing so, for example, in jQuery it was ajaxError() and ajaxSuccess(). The Node...