دانلود کتاب ساخت وب سایت های واکنشی با RxJS

The list of requirements for frontend work keeps increasing. 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: 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.