Introduction

In this section, we’ll build a shopping cart for our store. This will be one of the most advanced features we’ve built in this course, but we’re well-equipped to deal with the challenges that will come up.

A shopping cart

Shopping carts are an e-commerce feature that pretty much everyone uses. However, there are many different ways to build a shopping cart. We’ll start this section by laying out precisely what our cart needs to do, along with details on how we’ll go about building it. We’ll go step-by-step throughout the development process and end up with a working shopping cart powered by Channels.

Course roadmap

We’ll see almost every concept that we’ve discussed in the course so far throughout this section—we’ll be using Channels, PubSub, Channel state, JavaScript, and session state. We’ll consider many failures in our design, such as server crashes, user internet disconnections, and multi-tab support. We’ll perform manual acceptance tests against our shopping cart at the end of this section.

It’s essential to write unit tests for our code, but it takes many lessons to include and explain unit tests in a course. Instead, unit tests are provided in the source code that ships with this course. Tests are included for all of the significant modules we’ll build in this section. We create key modules with an information section telling us where to find the relevant tests.