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

Coroutines


Coroutines are a concurrency technique that allow for cooperative multitasking. What this means is that if one part of our application needs to perform part of a task, it can do so, and then hand control off to another part of the application. Think about a subroutine, or in more recent times, a function. These subroutines often rely on other subroutines. However, they don't just run in succession, they cooperate with one another.

In JavaScript, there's no intrinsic coroutine mechanism. Generators aren't coroutines, but they have similar properties. For example, generators can pause the execution of a function, yielding control to another context, then regain control and resume. This gets us partway there, but generators are for generating values, which isn't necessarily what we're after with coroutines. In this section, we'll look at some techniques for implementing coroutines in JavaScript using generators.

Creating coroutine functions

Generators give us most of what we need to...