mixin.js

var T2 = (()=>{
// todo: mixins collection
class Foo {
	foo () {
		this.__super();
		console.log(this.bar());
	}
	bar() {console.log('bar')}
} 

const SomeMixin = { foo: function () {console.log('mixin')} }

function mixinIt (Target, mixin) {

	class Target_ extends Target {}

	Object.keys(mixin).forEach((prop) => {
		if (typeof Target.prototype[prop] === 'function') {
			const oldMethod = Target.prototype[prop];
			Target_.prototype[prop] = function (...args) {
				debugger
				const newThis = Object.assign({},this,{__super: oldMethod });
				debugger;
				return mixin[prop].apply(newThis, args)
			};
        } else {
			Target_.prototype[prop] = mixin[prop];
        }
    })
	return Target_;
}

return mixinIt(Foo, SomeMixin)
// copy statics
})()