boxing.js

const box = (obj) => {
    return {
        get isBox() { 
            return true
        },
        get prop() {
            return obj
        },
        unbox() {
            let o = obj
            while(o.isBox) {
                o = o.prop
            }
            return o
        }
    }
}

const box1 = box({ a: 10 })
const box2 = box(box1)
const box3 = box(box2)

assert(box1.prop).toBe({ a: 10 });
assert(box2.prop.prop).toBe({ a: 10 });
assert(box3.prop.prop.prop).toBe({ a: 10 });

assert(box1.unbox()).toBe({ a: 10 });
assert(box2.unbox()).toBe({ a: 10 });
assert(box3.unbox()).toBe({ a: 10 });

const box4 = box('Nu privet!')
const box5 = box(box4)

assert(box4.prop).toBe('Nu privet!');
assert(box5.prop.prop).toBe('Nu privet!');

assert(box4.unbox()).toBe('Nu privet!');
assert(box5.unbox()).toBe('Nu privet!');