JavaScript Cookbook, 3rd Edition

Chapter 8. Classes

Is JavaScript an object-oriented programming language? The answer depends on who you ask (and how you phrase the question). But the general consensus is yes, with some caveats.

Outside of academic circles, object-oriented programming languages usually revolve around concepts like classes, interfaces, and inheritance. But until recently, JavaScript was an outlier—an object-oriented programming language built on functions and prototypes. Then, along came ES6, and all of sudden classes were available as a native language construct, muddying the waters. Was it just syntactic sugar or a major language evolution?

The answer lies somewhere in between. Overall, ES6 classes are a higher-level language feature built on the familiar foundation of JavaScript prototypes. But the mapping isn’t exact, and the class model introduces some new subtleties that aren’t completely captured in the prototype model. Furthermore, it’s likely that classes will support new object-oriented features in the future, pushing the two overlapping models farther apart.

The bottom line is this: today new development favors using classes, but prototype-based code is still common (and far from obsolete). This chapter focuses on common patterns using classes, but also explores prototypes.

Creating a Reusable Class

Problem

You want to create a reusable template for custom objects.

Solution

Use the class keyword, and give your class a name. Inside, add a constructor function that initializes your ...