Node.js Web Development - Fourth Edition

Understanding ES-2015 class definitions

This sort of object class definition is new to JavaScript with ES-2015. It simplifies defining classes over previous methods and brings JavaScript class definitions closer to the syntax in other languages. Under the hood, JavaScript classes still use prototype-based inheritance, but with a simpler syntax, and the coder doesn't even have to think about the object prototype.

We can reliably determine whether an object is a note with the instanceof operator:

$ node> const Note = require('./Note');> typeof Note'function'> const aNote = new Note('foo', 'The Rain In Spain', 'Falls mainly on the plain');> var notNote = {}> notNote instanceof Notefalse> aNote instanceof Notetrue> typeof aNote'object'

This shows ...