Originally JavaScript didn't support ``++class++``es, and class-like behavior had to be kludged using things like ``++prototype++`` assignments for "class" functions. Fortunately, ECMAScript 2015 added classes, so any lingering ``++prototype++`` uses should be converted to true ``++class++``es. The new syntax is more expressive and clearer, especially to those with experience in other languages.
Specifically, with ES2015, you should simply declare a ``++class++`` and define its methods inside the class declaration.