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
PacktPub.com
Contributors
Preface
Index

Working with localStorage


The localStorage object is available in all major browsers. It was introduced in HTML5. Local storage allows you to store data persistently on a user's computer. Unless your script or user explicitly want to clear the data, the data will remain.

Local storage follows the same origin policy. We will discuss origin policy in detail in the next chapter, but, for now, just understand that the same origin policies can restrict different websites and their access to a particular website's local storage. 

In addition, keep in mind that key-value pairs in local storage can only be string values. To store objects, you'll have toJSON.stringify them first.

Creating a local storage entry

We can add entries to local storage in a more intuitive and convenient way than cookies. Here's what the syntax looks like using localStorage.setItem(key, value):

localStorage.setItem('myKey', 'awesome value');
console.log('entry added');

Note

ThelocalStorage is a synchronous API. It'll block the...