Unlike most other languages, JavaScript’s object system is based on prototypes, not classes.

Unlike most other languages, JavaScript’s object system is based on prototypes, not classes. Unfortunately, most JavaScript developers don’t understand JavaScript’s object system, or how to put it to best use. Others do understand it, but want it to behave more like class based systems. The result is that JavaScript’s object system has a confusing split personality, which means that JavaScript developers need to know a bit about both prototypes and classes.