Book Image

Building Enterprise JavaScript Applications

By : Daniel Li
Book Image

Building Enterprise JavaScript Applications

By: Daniel Li

Overview of this book

With the over-abundance of tools in the JavaScript ecosystem, it's easy to feel lost. Build tools, package managers, loaders, bundlers, linters, compilers, transpilers, typecheckers - how do you make sense of it all? In this book, we will build a simple API and React application from scratch. We begin by setting up our development environment using Git, yarn, Babel, and ESLint. Then, we will use Express, Elasticsearch and JSON Web Tokens (JWTs) to build a stateless API service. For the front-end, we will use React, Redux, and Webpack. A central theme in the book is maintaining code quality. As such, we will enforce a Test-Driven Development (TDD) process using Selenium, Cucumber, Mocha, Sinon, and Istanbul. As we progress through the book, the focus will shift towards automation and infrastructure. You will learn to work with Continuous Integration (CI) servers like Jenkins, deploying services inside Docker containers, and run them on Kubernetes. By following this book, you would gain the skills needed to build robust, production-ready applications.
Table of Contents (26 chapters)
Title Page
Copyright and Credits
Dedication
Packt Upsell
Contributors
Preface
Free Chapter
1
The Importance of Good Code
Index

Modularizing our code


If you take a look inside the src/index.js file, you'll see that there are three top-level middleware functions—checkEmptyPayloadcheckContentTypeIsSet, and checkContentTypeIsJson—as well as an anonymous error handler function. These are prime candidates that we can extract into their own modules. So, let's get started!

Modularizing our middleware

Let's carry out this refactoring process in a new branch called create-user/refactor-modules:

$ git checkout -b create-user/refactor-modules

 

Then, create a directory at src/middlewares; this is where we will store all of our middleware modules. Inside it, create four files—one for each middleware function:

$ mkdir -p src/middlewares && cd src/middlewares
$ touch check-empty-payload.js \
  check-content-type-is-set.js \
  check-content-type-is-json.js \
  error-handler.js

Then, move the middleware functions from src/index.js into their corresponding file. For example, the checkEmptyPayload function should be moved to src...