Search icon CANCEL
Subscription
0
Cart icon
Your Cart (0 item)
Close icon
You have no products in your basket yet
Save more on your purchases now! discount-offer-chevron-icon
Savings automatically calculated. No voucher code required.
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Conferences
Free Learning
Arrow right icon
Arrow up icon
GO TO TOP
Learn ECMAScript

You're reading from   Learn ECMAScript Discover the latest ECMAScript features in order to write cleaner code and learn the fundamentals of JavaScript

Arrow left icon
Product type Paperback
Published in Feb 2018
Publisher
ISBN-13 9781788620062
Length 298 pages
Edition 2nd Edition
Languages
Arrow right icon
Authors (2):
Arrow left icon
Narayan Prusty Narayan Prusty
Author Profile Icon Narayan Prusty
Narayan Prusty
MEHUL MOHAN MEHUL MOHAN
Author Profile Icon MEHUL MOHAN
MEHUL MOHAN
Arrow right icon
View More author details
Toc

Table of Contents (14) Chapters Close

Preface 1. Getting Started with ECMAScript 2. Knowing Your Library FREE CHAPTER 3. Using Iterators 4. Asynchronous Programming 5. Modular Programming 6. Implementing the Reflect API 7. Proxies 8. Classes 9. JavaScript on the Web 10. Storage APIs in JavaScript 11. Web and Service Workers 12. Shared Memory and Atomics 13. Other Books You May Enjoy

JavaScript execution model

JavaScript code is executed in a single thread, that is, two pieces of a script cannot run at the same time. Each website opened in the browser gets a single thread for downloading, parsing, and executing the website, called the main thread.

The main thread also maintains a queue, which has asynchronous tasks queued to be executed one by one. These queued tasks can be event handlers, callbacks, or any other kind of task. New tasks are added to the queue as AJAX requests/responses happen, events occur, timers are registered, and more. One long-running queue task can stop the execution of all other queue tasks and the main script. The main thread executes the tasks in this queue whenever possible.

HTML5 introduced web workers, which are actual threads running parallel to the main thread. When a web worker finishes executing or needs to notify the main...
lock icon The rest of the chapter is locked
Register for a free Packt account to unlock a world of extra content!
A free Packt account unlocks extra newsletters, articles, discounted offers, and much more. Start advancing your knowledge today.
Unlock this book and the full library FREE for 7 days
Get unlimited access to 7000+ expert-authored eBooks and videos courses covering every tech area you can think of
Renews at $19.99/month. Cancel anytime