Book Image

Deno Web Development

By : Alexandre Portela dos Santos
Book Image

Deno Web Development

By: Alexandre Portela dos Santos

Overview of this book

Deno is a JavaScript and TypeScript runtime with secure defaults and a great developer experience. With Deno Web Development, you'll learn all about Deno's primitives, its principles, and how you can use them to build real-world applications. The book is divided into three main sections: an introduction to Deno, building an API from scratch, and testing and deploying a Deno application. The book starts by getting you up to speed with Deno's runtime and the reason why it was developed. You'll explore some of the concepts introduced by Node, why many of them transitioned into Deno, and why new features were introduced. After understanding Deno and why it was created, you will start to experiment with Deno, exploring the toolchain and writing simple scripts and CLI applications. As you progress to the second section, you will create a simple web application and then add more features to it. This application will evolve from a simple 'hello world' API to a web application connected to the database, with users, authentication, and a JavaScript client. In the third section, the book will take you through topics such as dependency management, configuration and testing, finishing with an application deployed in a cloud environment. By the end of this web development book, you will become comfortable with using Deno to create, maintain, and deploy secure and reliable web applications.
Table of Contents (15 chapters)
1
Section 1: Getting Familiar with Deno
5
Section 2: Building an Application
10
Section 3: Testing and Deploying

Using middleware functions

If you have used any HTTP framework, be it JavaScript or otherwise, you are probably familiar with the concept of middleware functions. If you are not, then no worries – that's what we'll explain in this section.

Let's start with a definition borrowed from the Express.js documentation (http://expressjs.com/en/guide/writing-middleware.html):

"Middleware functions are functions that have access to the request object (req), the response object (res), and the next middleware function in the application's request-response cycle. The next middleware function is commonly denoted by a variable named next."

Middleware functions intercept requests and have the ability to act on them. They can be used in many different use cases, as follows:

  • Changing the request and response objects
  • Ending the request-response life cycle (answering requests or skipping other handlers)
  • Calling...