Express in Action: Writing, building, and testing Node.js applications

403 Pages·2016·3.03 MB·English

by  Evan Hahn

MEAP Edition
Manning Early Access Program
Express in Action
Node applications with Express and its
companion tools
Version 10

Copyright 2015 Manning
Publications
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welcome
Thank you so much for purchasing the MEAP for Express in
Action! The book is really coming along, and I'm honored that
you'll join me as I continue to work on it. This is an intermediate-
level book aimed at intermediate-level JavaScript developers
who want to start building web applications with Express and
Node.js.
I've tried to make the content approachable to Node.js
beginners. I want to emphasize how Express works, not just
how to use it; I find this thinking invaluable when debugging and
when deciding how to architect my software. I also hope to
show how to extend Express with other tools to build rich web
applications.
In this MEAP, we've got seven chapters of the planned eleven
and an appendix.
The first chapter outlines Express at a high level, and is aptly-
named "What is Express?". It explains what the Express
framework is and isn't, its strengths and weaknesses, and its
major conceptual hurdles.
Chapter 2 aims to give you a solid understanding of Express's
foundations. It starts by focusing on low-level Node.js, and then
transitions to showing how to do the same things with Express
at a higher level. By the end of the chapter, you'll have a strong
understanding of the framework which we'll build on for the rest
understanding of the framework which we'll build on for the rest
of the book.
Chapter 4 digs into routing, which is one of Express's major
features. Routing allows Express to appropriately sort requests
coming into your website. The chapter starts with basic
examples but gets in-depth. If any of the basic web workings
confuse you, you can take a look at the appendix that describes
HTTP in detail.
Chapter 5 talks about dynamically-generated HTML templates.
We'll try both EJS and Jade, two popular templating engines for
Node.
Chapter 6 is a chapter about databases. There are very few web
applications that can function without some kind of data
storage, and this chapter tackles that with the MongoDB
database, a popular choice for Express developers.
Chapter 8 will have you setting up automated testing for your
Express applications. After you write automated tests, you'll be
much more confident that your code is robust and performing
as it should. We'll look at some of the helpful tools out there.
Chapter 10 takes your applications to the real world—you'll
deploy your applications to the Heroku cloud platform. You'll be
able to write Express applications and show them to the world.
This chapter also discusses compilation of assets, which
includes the packaging of JavaScript and CSS to speed up your
client-side resources.
Future chapters will discuss middleware in detail, how to secure
Express applications, techniques for building APIs, and how to
integrate Express with databases and real-time features.
I really hope you'll continue to give feedback in the Author
Online forum. I'll be reading and responding to all of your
comments, and your feedback is very helpful as I work on this
book!
Thanks again! Honored that you'd join me on this journey.

—Evan Hahn
brief contents
Part 1: Introduction
1 What is Express?
2 The Basics of Node.js
3 Foundations of Express
Part 2: Core Express
4 Middleware
5 Routing
6 Building APIs
Part 3: Express in Context
7 Views & Templates : Jade & EJS
8 Persisting your data with MongoDB
9 Testing Express Applications
10 Security
11 Deployment: Assets & Heroku
12 Best practices
Appendixes:
A Other Helpful Modules
1 What is Express?

Before we talk about Express, we need to talk about Node.js.
For most of its life, the JavaScript programming language has
lived inside of web browsers. It started as a simple scripting
language for modifying small details of webpages, but grew into
a complex language, with loads of applications and libraries.
Many browser vendors like Mozilla and Google began to pump
lots of resources into fast JavaScript runtimes, and Google
Chrome and Mozilla Firefox got much faster JavaScript engines
as a result.
In 2009, Node.js came around. Node took V8, Google Chrome's
powerful JavaScript engine, out of the browser and made it able
to run on servers. In the browser, developers had no choice but
to choose JavaScript. In addition to Ruby, Python, C#, Java, or
other languages, developers could now choose JavaScript when
developing server-side applications.
JavaScript might not be the perfect language for everyone, but
Node.js had some real benefits. For one, the V8 JavaScript
engine is fast, and Node encourages an asynchronous coding
style, making for faster code while avoiding multi-threaded
nightmares. JavaScript also had a bevy of useful libraries
because of its popularity. But the biggest benefit of Node.js is
the ability to share code between browser and server.
Developers don't have to do any kind of context switch when
switching between client and server. Now they can use the
same code and the same coding paradigms between two
same code and the same coding paradigms between two
different JavaScript runtimes; the browser and the server.
Node.js caught on—people thought it was pretty cool.
Like browser-based JavaScript, Node.js provides a bevy of low-
level features you'd need to build an application. But like
browser-based JavaScript, its low-level offerins can be a bit
verbose and difficult.
Enter Express.js. Express is a framework that acts as light layer
on top of the Node.js web server, making it more pleasant to
develop Node.js web applications.
Express.js is philosophically similar to jQuery. People want to
add dynamic content to their webpages, but the “vanilla”
browser APIs can be verbose, confusing, and limited in features.
Developers often have to write a lot of boilerplate code. jQuery
exists to cut down on this boilerplate code by simplifying the
APIs of the browser and adding helpful new features. That's
basically it.
Express is exactly the same. People want to make web
applications with Node.js, but the “vanilla” Node.js APIs can be
verbose, confusing, and limited in features. Developers often
have to write a lot of boilerplate code. Express exists to cut
down on this boilerplate code by simplifying the APIs of Node.js
and adding helpful new features. That's basically it!
Like jQuery, Express aims to be extensible. It's hands-off about
most parts of your applications' decisions and is easily extended
with third-party libraries. Throughout this book and your Express
career, you'll have to make decisions about your applications'
architectures and you'll extend Express with a bevy of powerful