representing null as constructor prototype

NullPrototype.js

'use strict';

const MyNull = function () {};
MyNull.prototype = null;
const s = new MyNull();

// as this might be only the object,
// so null would be converted
console.log(s);
console.log(s.valueOf());                        // {}

const s_proto = Object.getPrototypeOf(s);

console.log(s === s.valueOf());                 // true
console.log(s_proto);    // [Object: null prototype] {}

console.log(s instanceof Object)                // true
console.log(s_proto instanceof Object)          // false

console.log(typeof s_proto === 'object')        // true
console.log(s_proto == null)                    // false

console.log(s.valueOf() === s_proto.valueOf());  // false
console.log(s_proto.valueOf() === s_proto);      // true

// this is the end of Prototype Chain itself
console.log(Object.getPrototypeOf(s_proto));     // null


const AndNull = function () {};
AndNull.prototype = s_proto;

const z = new AndNull();

console.log(Object.getPrototypeOf(z));
console.log(Object.create(null));

// other primitives //
const AndNumber = function () {};
AndNull.prototype = 5;

const n = new AndNumber();

// here ther is no primitive value 
console.log(n);
console.log(Object.getPrototypeOf(n));

// but here, as it is wrapped, it is OK
const ButAndNumber = function () {};
ButAndNumber.prototype = new Number(5);

const nn = new ButAndNumber();

console.log(nn);
console.log(Object.getPrototypeOf(nn));
console.log(Object.getPrototypeOf(nn).valueOf());