$ cd /path/to/the/source/require_and_exports
$ node run.js

// scopes
$ cd /path/to/the/source/scopes
$ node run.js

// closures
$ cd /path/to/the/source/closures
$ node run.js

$ cd /path/to/the/source/this

// first example
$ node scope.js

// second example
$ node mistake.js

$ cd /path/to/the/source/callbacks

// how other language work
$ node normal.js

// shows you how things go without callback
$ node opposite.js

// how it works with callback
$ node callback.js

// showing the differences of differnet callbacks
$ node alternatives.js

$ cd /path/to/the/source/events/js

// wrong way without callbacks
$ node wrong.js

// right way with callbacks
$ node right.js

// using node.js events
$ cd /path/to/the/source/events/nodejs
$ node run.js