Node and Express

JavaScript has traditionally been used within web browsers in order to enhance or improve the usability or style of web pages. With the growth of the web, each browser competed to provide the best and fastest JavaScript engine they could. One of these JavaScript engines was the V8 engine, which was initially built for Google Chrome, and was released as open source in 2008. Using this engine, Ryan Dahl wrote a JavaScript engine that could be used as a web server, and run on the command line, named Node.js, or simply Node. A year after Node was released, the first versions of the Express framework for Node were released, which provided a set of features to simplify building server-side applications using JavaScript.

Node, using the single-threaded execution of JavaScript code, is able to handle thousands of concurrent web server requests from servers that are relatively small and cheap. Using the callback mechanisms of JavaScript, this also means that programmers...

Express introduction

In this section of the chapter, we will set up a Node and Express development environment, and show how to build the simplest web server with just a few lines of code. We will then discuss routes, and show how to split up our code base into modules for ease of maintenance and readability. Finally, we will discuss how to set configuration parameters for a Node application.

Express setup

In order to build a Node and Express application, we just need to initialize a Node environment, and install a few npm packages, as well as their corresponding declaration files as follows:

mkdir node-express-app
cd node-express-app
npm init
npm install express
npm install @types/express --save-dev

Here, we have created a directory named node-express-app, changed into this directory, and then initialized a Node environment. We then install the express module using npm, and install the TypeScript declaration files for Express, as in @types/express. We will also need...

An Express application

Now that we have an idea about the basics of Express routing and setup, let's build a two-page application that handles a user login form. Along the way, we will learn about how Express renders application HTML pages, how they can be combined with a generic layout page, and how to serve static files such as CSS and icons. We will also discuss how to handle form input, and how to use session data.

Express templating

Our current route handlers are returning simple messages to the browser. In a real-world application, however, we will need to render complete HTML pages, with a standard HTML structure, including links to CSS stylesheets if necessary, and a header section. Express uses a template engine that allows us to specify the HTML we need for each page, and also provides the mechanism of injecting run-time values into these templates, similar to the template mechanisms of Angular, React, or Vue.

Express supports many different templating engines...

Summary

In this chapter, we explored writing a Node application, and particularly a web application, using the Express library. We worked through setting up a very minimal Express application, and then went on to discuss Express routes and configuration. We then explored Express template engines, and installed and configured Handlebars to render two different pages, through our route handlers. We then discussed static files and implemented a login page, showing how to write data to session information. In the next chapter, we will explore the world of REST APIs, and build an API using Amazon Web Services.