Douglas Crockford on Class Free OOP in JavaScript

You should watch the whole video, he explains it at later in the video.

function constructor(spec) {
  let {member} = spec,
      {other}  = other_constructor(spec),
      method   = function () {
        // accesses member, other, method, spec
      };

  return Object.freeze({
      method,
      other
  });
}

It’s the revealing module pattern returning a frozen object.