Sharing code with the browser

One of the main selling points of Node.js is the fact that it's based on JavaScript and runs on V8, a JavaScript engine that actually powers some of the most popular browsers: Google Chrome and Microsoft Edge. We might think that sharing the same JavaScript engine is enough to make sharing code between Node.js and the browser an easy task; however, as we will see in this chapter, this is not always true, unless we want to share only simple, self-contained, and generic fragments of code.

Developing code for both the client and the server requires a non-negligible level of effort in making sure that the same code can run properly in two environments that are intrinsically different. For example, in Node.js, we don't have the DOM or long-living views, while on the browser, we surely don't have the filesystem and many other interfaces to interact with the underlying operating system.

Another contention point is the level of support...