const obj = {};
const arr = [1,2,3,4,5];
const objProto = Object.getPrototypeOf(obj);
const arrProto = Object.getPrototypeOf(arr);
const arrProto2 = Object.getPrototypeOf(arrProto);
objProto.foo = function(){
console.log('Hello World');
};
arr.foo(); // -> "Hello world"
console.log(arrProto2 === objProto); // -> true