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


The focus of this chapter has been the web browser platform and JavaScript's place within it. There are a lot of events taking place whenever we view and interact with web pages. These are processed as tasks, taken from queues. One such task is invoking the JavaScript interpreter with code to run.

When the JavaScript interpreter runs, it contains an execution context stack. A function, a module, and global script code—these are all examples of JavaScript execution contexts. The interpreter also has it's own internal job queues; one is used to create new execution context stacks, and another is used for calling promise resolution callback functions.

We wrote some code that manually created tasks using the setTImeout() function and explicitly demonstrated how long-running JavaScript code can be problematic for these tasks. We then looked at the EventTarget interface, used to listen to DOM events, and to network requests, amongst other things we didn't look at in this chapter, like web...