If you're reading this book, you might already have some idea of what React is. You also might have heard a React success story or two. If not, don't worry. I'll do my best to spare you from additional marketing literature in this opening chapter. However, this is a large book, with a lot of content, so I feel that setting the tone is an appropriate first step. Yes, the goal is to learn React and React Native. But, it's also to put together a lasting architecture that can handle everything we want to build with React today, and in the future.
This chapter starts with brief explanation of why React exists. Then, we'll talk about the simplicity that makes React an appealing technology and how React is able to handle many of the typical performance issues faced by web developers. Lastly, we'll go over the declarative philosophy of React and the level of abstraction that React programmers can expect to work with.
Let's go!
I think the one-line description of React on its homepage (https://facebook.github.io/react) is brilliant:
A JavaScript library for building user interfaces.
It's a library for building user interfaces. This is perfect, because as it turns out, this is all we want most of the time. I think the best part about this description is everything that it leaves out. It's not a mega framework. It's not a full-stack solution that's going to handle everything from the database to real-time updates over web socket connections. We don't actually want most of these pre-packaged solutions, because in the end, they usually cause more problems than they solve. Facebook sure did listen to what we want.
React is generally thought of as the view layer in an application. You might have used a library such as Handlebars or jQuery in the past. Just like jQuery manipulates UI elements, or Handlebars templates are inserted onto the page, React components change what the user sees. The following diagram illustrates where React fits in our frontend code:
This is literally all there is to React—the core concept. Of course there will be subtle variations to this theme as we make our way through the book, but the flow is more or less the same. We have some application logic that generates some data. We want to render this data to the UI, so we pass it to a React component, which handles the job of getting the HTML into the page.
You may wonder what the big deal is, especially since at the surface, React appears to be yet another rendering technology. We'll touch on some of the key areas where React can simplify application development in the remaining sections of the chapter.