Book Image

Mastering JavaScript

By : Ved Antani
Book Image

Mastering JavaScript

By: Ved Antani

Overview of this book

JavaScript is a high-level, dynamic, untyped, lightweight, and interpreted programming language. Along with HTML and CSS, it is one of the three essential technologies of World Wide Web content production, and is an open source and cross-platform technology. The majority of websites employ JavaScript, and it is well supported by all modern web browsers without plugins. However, the JavaScript landscape has changed dramatically in recent years, and you need to adapt to the new world of JavaScript that people now expect. Mastering modern JavaScript techniques and the toolchain are essential to develop web-scale applications. Mastering JavaScript will be your companion as you master JavaScript and build innovative web applications. To begin with, you will get familiarized with the language constructs and how to make code easy to organize. You will gain a concrete understanding of variable scoping, loops, and best practices on using types and data structures, as well as the coding style and recommended code organization patterns in JavaScript. The book will also teach you how to use arrays and objects as data structures. You will graduate from intermediate-level skills to advanced techniques as you come to understand crucial language concepts and design principles. You will learn about modern libraries and tools so you can write better code. By the end of the book, you will understand how reactive JavaScript is going to be the new paradigm.

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Mastering JavaScript
Ved Antani
Jan, 2016 | 250 pages
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Table of Contents (16 chapters)
Mastering JavaScript
Mastering JavaScript
Credits
Credits
About the Author
About the Author
About the Reviewer
About the Reviewer
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
JavaScript Primer
JavaScript Primer
A little bit of history
How to use this book
Hello World
Summary
2
Functions, Closures, and Modules
Functions, Closures, and Modules
A function literal
Functions as data
Scoping
Function declarations versus function expressions
The arguments parameter
Anonymous functions
Closures
Timers and callbacks
Private variables
Loops and closures
Modules
Summary
3
Data Structures and Manipulation
Data Structures and Manipulation
Regular expressions
Exact match
Match from a class of characters
Repeated occurrences
Beginning and end
Backreferences
Greedy and lazy quantifiers
Arrays
Maps
Sets
A matter of style
Summary
4
Object-Oriented JavaScript
Object-Oriented JavaScript
Understanding objects
Instance properties versus prototype properties
Inheritance
Getters and setters
Summary
5
JavaScript Patterns
JavaScript Patterns
Design patterns
The namespace pattern
The module pattern
The factory pattern
The mixin pattern
The decorator pattern
The observer pattern
JavaScript Model-View-* patterns
The Model-View-Presenter pattern
Model-View-ViewModel
Summary
6
Testing and Debugging
Testing and Debugging
Unit testing
JavaScript debugging
Summary
7
ECMAScript 6
ECMAScript 6
Shims or polyfills
Transpilers
ES6 syntax changes
Summary
8
DOM Manipulation and Events
DOM Manipulation and Events
DOM
Chaining
Traversal and manipulation
Working with browser events
Propagation
jQuery event handling and propagation
Event delegation
The event object
Summary
9
Server-Side JavaScript
Server-Side JavaScript
An asynchronous evented-model in a browser
Callbacks
Timers
EventEmitters
Modules
npm
JavaScript performance
Summary
Index
Index

Timers and callbacks

In implementing timers or callbacks, you need to call the handler asynchronously, mostly at a later point in time. Due to the asynchronous calls, we need to access variables from outside the scope in such functions. Consider the following example:

function delay(message) {
  setTimeout( function timerFn(){
    console.log( message );
  }, 1000 );
}
delay( "Hello World" );

We pass the inner timerFn() function to the built-in library function, setTimeout(). However, timerFn() has a scope closure over the scope of delay(), and hence it can reference the variable message.

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