上QQ阅读APP看书，第一时间看更新
The built-in module to use require()
Now, to kick things off, the first thing I will do is to use console.log to print Starting app, as shown in the following code:
console.log('Starting app');
The only reason we'll do this is to keep track of how our files are executing, and we'll do this only for the first project. Down the line, once you're comfortable with how files get loaded and how they run, we'll be able to remove these console.log statements, as they won't be necessary.
After we call the console.log starting app, we'll load in a built-in module using require().
We can get a complete list of all of the built-in modules in the Node.js API docs.
To view Node.js API docs, go to nodejs.org/api. When you go to this URL, you'll be greeted with a long list of built-in modules. Using the File System module we'll create a new file and the OS module. The OS module will let us fetch things such as the username for the currently logged-in user.