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
About the Author
About the Reviewer

Single threaded IO

A common misconception of NodeJS is that it's actually restricted to one CPU and can't achieve true parallelism. The fact is that Node often does use multiple threads of control. We'll explore these concepts later on in the chapter. Perhaps it's the IO event loop that's misleading because it does run in a single thread, on a single CPU.

The goal of this section is to introduce the concept of an IO loop, why it's a good idea for most web application back-ends, and how it overcomes challenges faced multithreading approaches to concurrency.


The following chapter covers more advanced Node concurrency topics, including the ways in which the event loop can bite us. While the event loop is a novel idea, it's not perfect; every solution to a given concurrency problem has negative trade-offs.

IO is slow

The slowest parts of a given web application infrastructure are the network IO and the storage IO. These operations are reasonably fast, mostly thanks to physical hardware improvements...