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

Implementing modules – the new way


There is a new way to import and export modules in JavaScript, that is the official module system. Since it is supported natively by the language, it can be referred to as the standard JavaScript module system. You should consider using the official module system in practice because it's native and thus optimized for speed and performance.

Importing/exporting modules

Let's say you're coding a module file and now you're ready to import it into your main file. How will you export it using the official module system? Here's how:

// module.js

const takeSquareAndAdd2 = num => {
    return num*num + 2;
}

export { takeSquareAndAdd2 }; // #1
export const someVariable = 100; // #2
export function yourName(name) {
    return `Your name ${name} is a nice name` 
}; // #3
export default "Holy moly this is interesting!" // #4
  • #1: We've first coded a function and then, using the export keyword, made it available to other modules that import this particular module.
  • #2...