Book Image

Learn ECMAScript - Second Edition

By : MEHUL MOHAN, Narayan Prusty
Book Image

Learn ECMAScript - Second Edition

By: MEHUL MOHAN, Narayan Prusty

Overview of this book

Learn ECMAScript explores implementation of the latest ECMAScript features to add to your developer toolbox, helping you to progress to an advanced level. Learn to add 1 to a variable andsafely access shared memory data within multiple threads to avoid race conditions. You’ll start the book by building on your existing knowledge of JavaScript, covering performing arithmetic operations, using arrow functions and dealing with closures. Next, you will grasp the most commonly used ECMAScript skills such as reflection, proxies, and classes. Furthermore, you’ll learn modularizing the JS code base, implementing JS on the web and how the modern HTML5 + JS APIs provide power to developers on the web. Finally, you will learn the deeper parts of the language, which include making JavaScript multithreaded with dedicated and shared web workers, memory management, shared memory, and atomics. It doesn’t end here; this book is 100% compatible with ES.Next. By the end of this book, you'll have fully mastered all the features of ECMAScript!
Table of Contents (18 chapters)
Title Page

Proxies in a nutshell

A proxy acts like a wrapper for an object and defines the custom behavior for the fundamental operations on the object. Some fundamental operations on the objects are property lookup, property assignment, constructor invocation, enumeration, and so on.

Think of it as a basic way of intercepting the operation you do with an object and its associated properties. For example, calling out a property value by writing <objectname>.propertyName should technically just echo out the property value, right?

What if you want to take a step back and inject your control right before the echoing part, but right after the calling part? Here's where proxies come in.

Once an object is wrapped using a proxy, all the operations that are supposed to be done on the object should now be done on the proxy object, so that the custom behavior can take place.

Terminology for proxies

Here are some important terms that are used while studying proxies:

  • Target: This is the object that is wrapped...