Once we have built our Catalog, it is time to add a cart to our application. When our code begins to grow, it's necessary to split it in several parts to keep it maintainable. When we split JavaScript code, we are talking about modules, classes, function, libraries, and so on. When we talk about HTML, we call these parts templates.

KnockoutJS has a native template engine that we can use to manage our HTML. It is very simple, but also has a big inconvenience: templates, it should be loaded in the current HTML page. This is not a problem if our app is small, but it could be a problem if our application begins to need more and more templates.

In this chapter, we are going to design our templates with the native engine and then we will speak about mechanisms and external libraries we can use to improve the Knockout template engine.