Preface

Some applications just get it right. These are the exceptions rather than the rule. Lots of JavaScript applications get one or two things right, and other things very wrong. The things we get wrong are a side effect of the scaling influencers that we never considered. This is a book about scaling our frontend architectures to meet the quality requirements asked of us. Scaling JavaScript applications is an interesting and fun problem. There're so many moving parts—the users, the developers, the deployment environments, the browser environments, and the task of bringing all of these factors together to form a meaningful user experience. What are we scaling, and why? The aim of this book is to help us answer these questions.

What this book covers

Chapter 1, Scale from a JavaScript Perspective, introduces the idea of scalable JavaScript applications and what makes them different from other applications that scale.

Chapter 2, Influencers of Scale, helps us understand that the need to scale helps us design better architectures.

Chapter 3, Component Composition, explains how the patterns that form the core of our architecture serve as blueprints for assembling components.

Chapter 4, Component Communication and Responsibilities, explains how components that communicate with one another are a scaling constraint. It tells us how features are the result of component communication patterns.

Chapter 5, Addressability and Navigation, elaborates on large-scale web applications with URIs that point to resources, and how designs that scale can handle a growing number of URIs.

Chapter 6, User Preferences and Defaults, tells us why users need control over certain aspects of our software. And it also explains that scalable application components are configurable.

Chapter 7, Load Time and Responsiveness, explains how more moving parts means performance degradation across the application. This includes making trade-offs that keep our UI responsive, while adding new features.

Chapter 8, Portability and Testing, covers writing JavaScript code that's not tightly coupled with a single environment. This includes creating portable mock data and portable tests.

Chapter 9, Scaling Down, explains how removing unused or buggy components from applications is essential, if we want to scale up in other areas.

Chapter 10, Coping with Failure, explains that large-scale JavaScript architectures can't fall over as a result of a bug in one component. This includes how designing with failure in mind is the key to achieving scale in a broad number of scenarios.

What you need for this book

• NodeJS
• Code Editor/IDE
• A modern Web browser

Who this book is for

This book is intended for a senior JavaScript developer who is curious about architectural issues in the frontend. There's no prerequisite framework knowledge required, however, most of the concepts presented throughout the book are adaptations of components found in frameworks such as Backbone, Angular, or Ember. Strong JavaScript language skills are required, and all code examples are presented using ECMAScript 6 syntax.

Conventions

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, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: " For example, users/31729. Here, the router will need to find a pattern that matches this string, and the pattern will also specify how to extract the 31729 variable."

A block of code is set as follows:

// Renders the sections of the view. Each section
    // either has a renderer, or it doesn't. Either way,
    // content is returned.
    render() {

Note

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