Book Image

JavaScript Concurrency

By : Adam Boduch
Book Image

JavaScript Concurrency

By: Adam Boduch

Overview of this book

Concurrent programming may sound abstract and complex, but it helps to deliver a better user experience. With single threaded JavaScript, applications lack dynamism. This means that when JavaScript code is running, nothing else can happen. The DOM can’t update, which means the UI freezes. In a world where users expect speed and responsiveness – in all senses of the word – this is something no developer can afford. Fortunately, JavaScript has evolved to adopt concurrent capabilities – one of the reasons why it is still at the forefront of modern web development. This book helps you dive into concurrent JavaScript, and demonstrates how to apply its core principles and key techniques and tools to a range of complex development challenges. Built around the three core principles of concurrency – parallelism, synchronization, and conservation – you’ll learn everything you need to unlock a more efficient and dynamic JavaScript, to lay the foundations of even better user experiences. Throughout the book you’ll learn how to put these principles into action by using a range of development approaches. Covering everything from JavaScript promises, web workers, generators and functional programming techniques, everything you learn will have a real impact on the performance of your applications. You’ll also learn how to move between client and server, for a more frictionless and fully realized approach to development. With further guidance on concurrent programming with Node.js, JavaScript Concurrency is committed to making you a better web developer. The best developers know that great design is about more than the UI – with concurrency, you can be confident every your project will be expertly designed to guarantee its dynamism and power.
Table of Contents (17 chapters)
JavaScript Concurrency
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Concurrency challenges with this model


We'll wrap this chapter up with a discussion on the challenges that this execution model poses with JavaScript concurrency. There are two fundamental obstacles. The first is the fact that no matter what, any JavaScript code that runs will block anything else from happening. The second obstacle is trying to synchronize asynchronous actions with callback functions, leading to callback hell.

Limited opportunity for parallelism

It used to be that the lack of parallelism in JavaScript wasn't really an issue. Nobody missed it because JavaScript was viewed as a progressive enhancement tool for HTML pages. This changed when the front-end started taking on more responsibilities. These days, the majority of the application actually resides in the front-end. This allows back-end components to focus on problems that can't be solved by JavaScript (from a browser perspective, NodeJS is another matter entirely that we'll look at later in the book).

For example, mapping...