var a = {a: 1} var b = Object.create(a) console.log(a) and console.log(b) a.a = 2 console.log(b.a) The interviewer got confused and said that the prototype is copied to b and if we change a.a it will not have any impact on b.a. But rather b's __proto__ will have a link to a and if we change or delete a.a it will be reflected in b