Build Reactive Websites With Rxjs Randall Koutnik by Randall Koutnik instant download after payment.

You now need to build websites that load quickly on shaky

connections, render perfectly on mobile devices, and respond

with lightning speed to user input. All of these tasks require

dealing with a high number of events from disparate sources,

be it your CRM, late-breaking news, or just a chat room. The

topic of this book, observables, is a new way of thinking about

managing these events, even when they may occur sometime

in the future. Observables are a neat concept, but what’s

important is that you can keep things straight in your head,

allowing you to build bigger, faster, and less-buggy

applications for your users.

It’s important to ask, with such a big claim as “simplifying

frontend development,” what exactly is simplified? While

RxJS (short for “Reactive eXtensions to JavaScript”) brings

simplicity to many areas, this book focuses on two areas that

can have you reaching for the aspirin time and time again:

Asynchronous Calls and Control Flow

JavaScript’s async-first design has been both a blessing and a

curse. While the event loop allows us to fire off AJAX calls

with ease, keeping track of them all can be quite the chore. A

single AJAX request can be modeled as a promise, but more

than one suddenly means there’s a cacophony of items to

manually track (and even cancel) as the user progresses

through our app. One of the most notorious examples, the

typeahead, will be covered in Chapter 4, Advanced Async.

You’ll learn how to delegate both the calls and control flow to

RxJS, allowing you to focus on the rest of your application.

State Management

On the other hand, managing an application’s state has been

the bane of programmers since RAM was invented, leading to

the oft-quoted advice to “turn it off and on again,” resetting the

computer’s state. JavaScript makes this worse by defaulting to

a global, mutable state. In recent years, the JavaScript

community has started to build some impressive solutions