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

Using modules on the web

Modern browsers have very recently started to implement module loaders natively. To natively use a script that imports modules, you'll have to make its type="module".

Here's a very basic working example in Chrome 63:

// index.html
<!doctype HTML>
        <script src="index.js" type="module"></script>
        <div id="text"></div>

This is how index.js (the main script file) will look:

// index.js
import { writeText2Div as write2Div } from './module.js';
write2Div('Hello world!')

This is the module that index.js imports (in the same directory):

// module.js
const writeText2Div = text => document.getElementByID('text').innerText = text;
export { writeText2Div };

This, when tested, should show Hello World on the screen.