Object oriented code JS manual

oop.js

const interface_method = (object, _interface)=>(method) => (
        object._interface[_interface].hasOwnProperty(method) 
    && (typeof object._interface[_interface][method]) == "function"
)
const implInterface = (_interface, invariant, object, impl) => {
    if (!object.hasOwnProperty("_interface")) {
        object._interface = {};
    }
    object._interface[_interface] = impl
    if (!invariant(object)) {throw `FAILED TO IMPLEMENT \`${_interface}\``}
}


const IPerson = (object) =>{ 
    let method = interface_method(object, "IPerson");
    return method("name") && method("age");
}  
const implIPerson = (object, impl) => {
    implInterface("IPerson", IPerson, object, impl)
}

const ICompany = (object) => {
    let method = interface_method(object, "ICompany");
    return method("company");
}
const implICompany = (object, impl) => {
    implInterface("ICompany", ICompany, object, impl)
}
const IAge = (object) => {
    let method = interface_method(object, "IAge");
    return method("age");
}
const implIAge = (object, impl) => {
    implInterface("IAge", IAge, object, impl)
}

const ClassPerson = (name, age) => {  
    // method dispatch
    return {name : ()=>name, age : ()=>age}
}
const ClassEmployee = (name, age, company) => {
    let person = ClassPerson(name, age);
    person.company = ()=>company;
    return person;
}
const ClassEmployee2 = (person, company) => {
    person.company = ()=>company;
    return person;
}
const ClassHPEmployee = (person, gender) => {
    let still_at_hp = true;
    person.company = ()=>{ 
        still_at_hp = !still_at_hp;
        if (still_at_hp) { return "HP" }
        else {return "IBM" }
    };
    let old_name = person.name;
    person.name = ()=> 
        `${ (gender === "male" || gender === "Male" ) 
        ? "Mr" 
        : "Ms" 
        }.${old_name()}`;
        
    implIPerson(
        person, 
      { 
        name : old_name, 
        age : person.age
    });
    implICompany(
        person,
        { company : person.company }
    )
    implIAge(person, {age : person._interface.IPerson.age})
    return person;
}

const ClassComputer = (maker, {year, model}) => {
    let computer = {model : model, year : year};
    implICompany(computer, {company : ()=>maker})
    implIAge(computer, {age : ()=>(new Date().getFullYear()) - year})
    return computer;
}


const ask_for_age = (obj /* expects IPerson */) => {
    obj._interface.IPerson.age
}

//    forall O where O : IAge + ICompany =>
const age_and_company = (obj) => {
    let obji = obj._interface; 
    return { company : obji.ICompany.company(),
      age: obji.IAge.age()
    }
}

const e = ClassHPEmployee(ClassPerson("Bob", 55), "Male");
const c = ClassComputer("Apple", {year : 1977  ,model : "Apple2"});


let name = e.name();

console.log(e._interface.IPerson.name());
console.log(e);
console.log(c);
console.log(age_and_company(e));
console.log(age_and_company(c));

console.log(e.company());
console.log(e.company());
console.log(e.company());