function shouldBe(actual, expected) { if (actual !== expected) throw new Error('bad value: ' + actual); } function testFunction(func) { var array = Object.getOwnPropertyNames(func); shouldBe(array.indexOf("arguments"), -1); shouldBe(array.indexOf("caller"), -1); } testFunction((() => { }).bind()); testFunction((() => { "use strict"; }).bind()); testFunction((function () { }).bind()); testFunction((function () { "use strict"; }).bind());