An object of any type, much like our primitive values, should only be used inline with the semantic concept it represents. The preceding case of subclassing Array to HeartArray makes sense as the data we wish to express via it is indeed array-like, that is, it is a sequential set of words.

When we go about molding objects into abstractions that suit our needs, we should always consider the expectations that other programmers will have about objects and the ramifications of those expectations. We'll go into the subtleties of designing good abstractions in Chapter 11, Design Patterns, where we will be utilizing objects to craft abstractions in a multitude of ways.

This section has introduced you to the concept of objects in JavaScript—how they are everywhere—and how they operate beneath the surface via prototypes. This fundamental knowledge will make working with JavaScript much easier and will help you write cleaner code.