Chapter 1, A Refresher on jQuery and the Composite Pattern, will teach the reader how to write the code using the Composite Pattern and method chaining (Fluent Interface) by analyzing how they are used for the implementation of jQuery itself. It also demonstrates the Iterator Pattern that nicely pairs with the Composite Collection objects that jQuery returns.

Chapter 2, The Observer Pattern, will teach you how to respond to user actions using the Observer Pattern. It also demonstrates how to use Event Delegation as a way to reduce the memory consumption and complexity of the code that handles dynamically injected page elements. Finally, it will teach you how to emit and listen for Custom Events in order to achieve greater flexibility and code decoupling.

Chapter 3, The Publish/Subscribe Pattern, will teach you how to utilize the Pub/Sub Pattern to create a central point to emit and receive application-level events, as a way to decouple your code and business logic from the HTML that is used for presentation.

Chapter 4, Divide and Conquer with the Module Pattern, demonstrates and compares some of the most commonly used Module Patterns in the industry. It will teach you how to structure your application in small independent Modules using Namespacing, leading to expandable implementations that follow the Separation of Concerns principle.

Chapter 5, The Facade Pattern, will teach you how to use the Facade Pattern to wrap complex APIs into simpler ones that are a better match for the needs of your application. It also demonstrates how to change parts of your application, while keeping the same module-level APIs and avoid affecting the rest of your implementation.

Chapter 6, The Builder and Factory Patterns, explains the concepts of and the differences between the Builder and Factory Patterns. It will teach you how and when to use each of them, in order to improve the clarity of your code by abstracting the generation of complex results into separate dedicated methods.

Chapter 7, Asynchronous Control Flow Patterns, will explain how jQuery's Deferred and Promise APIs work and compare them with the classical Callbacks Pattern. You will learn how to use Promises to control the the execution of asynchronous procedures to run either in an order or parallel to each other.

Chapter 8, Mock Object Pattern, teaches you how to create and use Mock Objects and Services as a way to ease the development of your application and get a sense of its functionality, long before all its parts are completed.

Chapter 9, Client-side Templating, demonstrates how to use the Underscore.js and Handlebars.js templating libraries as a better and faster way to create complex HTML structures with JavaScript. Through this chapter, you will get an overview of their conventions, evaluate their features, and find the one that best matches your taste.

Chapter 10, Plugin and Widget Development Patterns, introduces the basic concepts and conventions of jQuery Plugin development and analyzes the most commonly used design patterns, so that you will be able to identify and use the best match for any use case.

Chapter 11, Optimization Patterns, guides you with the best tips to create a highly efficient and robust implementation. You will be able to use this chapter as a checklist of best practices that improve the performance and lower the memory consumption of your applications, before moving them to a production environment.

In order to run the examples in this book, you will need to have a web server installed on your system to serve the code files. For example, you can use Apache or IIS or NGINX. In order to make the installation process of Apache easier, you can use more complete development environment solutions, such as XAMPP or WAMP Server.

In terms of technical proficiency, this book assumes that you already have some experience of working with jQuery, HTML, CSS, and JSON. All the code samples in the book use jQuery v2.2.0 and some of the chapters also discuss the respective implementation in jQuery v1.12.0, which can be used in case support for older browsers is needed.

This book targets existing jQuery developers or new developers who want to take their skills and understanding to an advanced level. It is a detailed introduction to how the various industry standard patterns can be applied to jQuery applications, and along with a set of the best practices, it can help large teams collaborate and create well organized and extendable implementations.

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "In the preceding CSS code, we first defined some basic styles for the box, boxsizer, and clear CSS classes."

A block of code is set as follows:

$.each([3, 5, 7], function(index){
    console.log(this + 1 + '!');
});

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

$('#categoriesSelector').change(function() { 
    var $selector = $(this); 
    var message = { categoryID: $selector.val() }; 
    broker.trigger('dashboardCategorySelect', [message]); 
});

We are following Google's JavaScript Style Guide, except from using four spaces for indentation, in order to improve the readability of the code in the book. In short, we are placing curly brackets on top and use single quotes for string literals.

Any command-line input or output is written as follows:

npm install jquery

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "The jQuery Object returned is an Array-like object that acts as a wrapper object and carries the collection of the retrieved elements."

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To send us general feedback, simply e-mail <[email protected]>, and mention the book's title in the subject of your message.

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