inherits, as implemented in NodeJS circa ES5, but also defining superClass_ to maintain compatibility with existing in-browser inherits implementations.

util.inherits.js

'use strict';

function inherits(ctor, superCtor) {
  ctor.superClass_ = ctor.super_ = superCtor;
  ctor.prototype = Object.create(superCtor.prototype, {
    constructor: {
      value: ctor,
      enumerable: false,
      writable: true,
      configurable: true,
    },
  });
}