Programming javascript Applications Robust Web Architecture with Node, HTML5, and Modern JS Libraries

253 Pages·2014·8.13 MB·English

by  Eric Elliott

Programming JavaScript
Applications
Eric Elliott
Programming JavaScript Applications
by Eric Elliott
Copyright © 2014 Eric Elliott. All rights reserved.
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ISBN: 978-1-491-95029-6
[LSI]
Table of Contents
Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
1. The JavaScript Revolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Advantages of JavaScript 2
Performance 2
Objects 2
Syntax 3
First-Class Functions 3
Events 3
Reusability 4
The Net Result 4
Anatomy of a Typical Modern JavaScript App 4
Infrastructure 4
JSON: Data Storage and Communication 5
NoSQL Data Stores 6
RESTful JSON Web Services 6
2. Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Minimize Side Effects 10
Function Definition 12
Named Function Expressions 14
Lambdas 16
Immediately Invoked Function Expressions 18
Method Context 20
Function Scope 22
Hoisting 22
Closures 25
Method Design 27
Named Parameters 28
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Function Polymorphism 29
Generics and Collection Polymorphism 32
Method Chaining and Fluent APIs 35
Functional Programming 36
Stateless Functions (aka Pure Functions) 38
Partial Application and Currying 40
Asynchronous Operations 41
Callbacks 41
Promises and Deferreds 42
Conclusion 44
3. Objects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Classical Inheritance Is Obsolete 48
Fluent-Style JavaScript 51
Prototypes 53
Delegate Prototypes 53
Prototype Cloning 56
The Flyweight Pattern 57
Object Creation 59
Factories 61
Prototypal Inheritance with Stamps 64
Conclusion 69
4. Modules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Principles of Modularity 72
Interfaces 73
The Module Pattern 77
Asynchronous Module Definition 79
Plug-Ins 81
Node-Style Modules 82
npm 84
ES6 Modules 86
Building Client-Side Code with CommonJS, npm, Grunt, and Browserify 87
Defining the App 87
Feature Implementation 90
Bundling and Deployment 93
Conclusion 98
5. Separation of Concerns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Client-Side Concerns 100
Module Management 101
Events 106
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Model View Controller/MV* 114
Presentation and DOM Manipulation 117
Server-Side Concerns 125
Getting Started with Node and Express 125
Conclusion 134
6. Access Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Authentication 137
Passwords 137
Credential 141
Multifactor Authentication 143
Federated and Delegated Authentication 145
Authorization 147
Authorizing Applications 148
OAuth 2.0 149
Conclusion 150
7. Logging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Debugging 151
Server Operations 153
Security 153
Auditing 154
Business Analytics 154
Viral Factor 155
Logging Checklist 155
Logging Requests 156
Logging Errors 160
Sample Log Output 162
Logging Service Alerts 165
Logging Goals 166
Profiling and Instrumentation 166
Logging Client-Side Events 167
Deciphering Data 168
Conclusion 169
8. Building RESTful APIs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Usable 172
Focus 172
Consistency 174
Self-Describing: Hypermedia 182
Affordances 182
HATEOAS 183
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HTML as an API Media Type 185
Jade 185
Jiron 187
Responsive APIs 189
Optimizing for Speed 191
Conclusion 192
9. Feature Toggle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Organizing Features 193
Scale of a Feature 193
Feature Groups 194
Lifespan of a Feature 195
Development 195
Staging 195
Production Testing 195
Feature Rollout 195
Default Activation 196
Full Integration 196
Implementation 196
Conclusion 200
10. Internationalization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Conclusion 205
A. JavaScript Style Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
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Preface
Introduction
There are many books on the web technologies covered in this publication. However,
there are precious few on JavaScript that can be recommended to somebody who wants
to learn how to build a complete JavaScript application from the ground up. Meanwhile,
almost every new tech startup needs knowledgeable JavaScript application developers
on staff. This book exists for one purpose: to help you gain the knowledge you need to
build complete JavaScript applications that are easy to extend and maintain.
This book is not intended to teach you the basics of JavaScript. Instead, it’s designed to
build on your existing knowledge and discuss JavaScript features and techniques that
will make your code easier to work with over time. Normally, as an application grows,
it becomes increasingly difficult to add new features and fix bugs. Your code becomes
too rigid and fragile, and even a small change could necessitate a lengthy refactor. If you
follow the patterns outlined in this book, your code will remain flexible and resilient.
Changes to one piece of code won’t negatively impact another.
This book will focus primarily on client-side architecture, although it will also cover
server-side topics, such as basic RESTful APIs and Node. The trend is that a great deal
of the application logic is getting pushed to the client. It was once the case that the server
environment would handle things like templating and communication with vendor
services. Now, it’s common to deal with both of those jobs inside the browser.
In fact, a modern JavaScript application does almost everything a traditional desktop
app would do completely in the browser. Of course, servers are still handy. Server roles
frequently include serving static content and dynamically loaded modules, data persis‐
tence, action logging, and interfacing with third-party APIs.
vii
We’ll cover:
• JavaScript features and best practices for application developers
• Code organization, modularity, and reuse
• Separation of concerns on the client side (MVC, etc.)
• Communicating with servers and APIs
• Designing and programming RESTful APIs with Node.js
• Building, testing, collaboration, deployment, and scaling
• Expanding reach via internationalization
Who This Book Is For
You have some experience with JavaScript; at least a year or two working frequently with
the language, but you want to learn more about how you can apply it specifically to
developing robust web-scale or enterprise applications.
You know a thing or two about programming, but you have an insatiable thirst to learn
more. In particular, you’d like to learn more about how to apply the powerful features
that distinguish JavaScript from other languages, such as closures, functional program‐
ming, and prototypal inheritance (even if this is the first you’ve heard of them).
Perhaps you’d also like to learn about how to apply test-driven development (TDD)
techniques to your next JavaScript challenge. This book uses tests throughout the code
examples. By the time you reach the end, you should be in the habit of thinking about
how you’ll test the code you write.
Who This Book Is Not For
This book covers a lot of ground quickly. It was not written with the beginner in mind,
but if you need clarification, you might find it in JavaScript: The Good Parts, by Douglas
Crockford (O’Reilly, 2008), JavaScript: The Definitive Guide, by David Flannagan
(O’Reilly, 2011), or for help with software design patterns, the famous Gang of Four
book (GoF), Design Patterns: Elements of Reusable Object-Oriented Software, by Erich
Gamma, Richard Helm, Ralph Johnson, and John Vlissides (Addison-Wesley, 1994).
Google and Wikipedia can be handy guides to help you through, as well. Wikipedia is
a fairly good reference for software design patterns.
If this is your first exposure to JavaScript, you would do well to study some introductory
texts and tutorials before you attempt to tackle this book. My favorite is Eloquent Java‐
Script by Marijn Haverbeke (No Starch Press, 2011). Be sure to follow that up with
viii | Preface