In this section, you will finally learn some Node.js code, and we'll kick things off by talking about modules inside Node. Modules are units of functionality, so imagine I create a few functions that do something similar, such as a few functions that help with math problems, for example, add, subtract, and divide. I could bundle those up as a module, call it Andrew-math, and other people could take advantage of it.

Now, we'll not be looking at how to make our own module; in fact, we will be looking at how we can use modules, and that will be done using a function in Node, called require(). The require() function will let us do three things:

• First, it'll let us load in modules that come bundled with Node.js. These include the HTTP module, which lets us make a web server, and the fs module, which lets us access the filesystem for our machine.

In this section, you will learn how to use require() to load in other files that you created inside your project. This will let you move functions outside app.js into more specific files; this will make your application easier to scale, test, and update. To get started, the first thing we'll do is to make a new file.

In the context of our notes app, the new file will store various functions for writing and reading notes. As of now, you don't need to worry about that functionality, as we'll get into the detail later in the section, but we will create the file where it will eventually live. This file will be notes.js, and we'll save it inside the root...

You now know two out of the three ways to use require(), and in this section, we'll explore the last way, which is to require a package you've installed from npm. As I mentioned in the first chapter, npm is a big part of what makes Node so fantastic. There is a huge community of developers that have created thousands of packages that already solve some of the most common problems in Node applications. We will be taking advantage of quite a few packages throughout the book.

Now, in the npm packages, there's nothing magical, it's regular Node code that aims to solve a specific problem. The reason you'd want to use it is so you don't have to...

One of the major complaints I get is the fact that students have to restart the app from the Terminal every time they want to see the changes they just made inside their text editor. So, in this section, we'll take a look at how we can automatically restart our app as we make changes to the file. That means if I change from Gary to Mike and save it, it will automatically restart over in the Terminal.

Now, to automatically restart our app as we make changes to a file, we have to install a command-line utility, and we'll do this using npm. To get started, we'll go to Google Chrome (or the browser you are using) and head over to https://www.npmjs.com, as we did previously...

If a user wants to add a note, we need to know the note's title as well as the body of the note. If they want to fetch a note, we need to know the title of the note they want to fetch, and all this information needs to come into our app. And note apps, don't really do anything cool until they get this dynamic user input. This is what makes your scripts useful and awesome.

Now, throughout the book, we'll be creating note apps that get input from the user in a lot of different ways. We'll be using socket I/O to get real-time info from a web app, we'll be creating our own API so other websites and servers can make Ajax requests to our app, but in this section, we'll start things off with a very basic example of how to get user input.

We'll be getting input from the user inside the command line. That means when you run the app in the...

In this chapter, we learned how to use require to load in modules that come with Node.js. We created our files for our notes application and required them inside app.js. We explored how to use built-in modules and we explored how to use modules we defined. We found out how to require other files that we created, and how to export things such as properties and functions from those files.

We explored npm a little bit, how we can use npm init to generate a package.json file, and how we can install and use third-party modules. Next, we explored the nodemon module, using it to automatically restart our app as we make changes to a file. Last, we learned how to get input from the user, which is needed to create the notes application. We learned that we can use command-line arguments to pass data into our app.

In the next chapter, we'll explore some more interesting Node...