es6.js

"use strict";

var Root = class {
  constructor(name) { this.name = name; this.getName = this.getName.bind(this); }
  getName() { return this.name; }
  getNameOrig() { return this.name; }
};

var Child = class extends Root { }

transpiled.js

"use strict";

var Root = function(name) { this.name = name; this.getName = this.getName.bind(this); }
Root.prototype.getName = function() { return this.name; };
Root.prototype.getNameOrig = function() { return this.name; };

var Child = function() { Root.apply(this, arguments); }
Child.prototype = Object.create(Root.prototype);
Child.__proto__ = Root;