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
Packt Upsell
Free Chapter
The Importance of Good Code

High scalability

Scalability is a measure of how well a system can grow in order to handle higher demands, while still maintaining the same levels of performance.

The demand may arise as part of a sustained growth in user uptake, or it may be due to a sudden peak of traffic (for example, a food delivery application is likely to receive more requests during lunch hours).

A highly scalable system should constantly monitor its constituent components and identify components which are working above a "safe" resource limit, and scale that component either horizontally or vertically.

We can increase scalability in two ways:

  • Scale Vertically or scaling Up: Increase the amount of resources (for example, CPU, RAM, storage, bandwidth) to the existing servers
  • Scale Horizontally or scaling out: Adding servers to the existing cluster

Scaling vertically is simple, but there'll always be a limit as to how much CPU, RAM, bandwidth, ports, and even processes the machine can handle. For example, many kernels have...