es5-constructor.js

'use strict';

const ITER = 1e7;


function Foo() {
  this.futz = this.constructor.futz;
}
Foo.futz = false;

function Bar() {
  Foo.call(this);
}
Bar.__proto__ = Foo;
Bar.prototype.__proto__ = Foo.prototype;


let t = performance.now();

for (var i = 0; i < ITER; i++) {
  new Bar();
}

t = performance.now() - t;

print(((t * 1e6) / ITER).toFixed(1) + ' ns/op');

// 25 ns/op

es6-constructor.js

'use strict';

class Foo {
  constructor() {
    this.futz = this.constructor.futz;
  }
}
Foo.futz = false;

class Bar extends Foo {
  constructor() {
    super();
  }
}


let t = performance.now();

for (var i = 0; i < ITER; i++) {
  new Bar();
}

t = performance.now() - t;

print(((t * 1e6) / ITER).toFixed(1) + ' ns/op');

// 180 ns/op