He creado objetos y prototipos en ES5, ahora quiero crear un nuevo prototipo que agrupe objetos existentes, tengo este código

 const person = function(firstName,lastName){ this.firstName =firstName; this.LastName = lastName; this.getFullName = function () { return firstName + ' ' + lastName ; }; this.setFullName = function(firstName, lastName) { firstName = firstName.split(' ')[0]; lastName = lastName.split(' ')[1]; }; };

Creé un prototipo de estudiante que es una extensión de la clase persona

 const student = function(firstName,lastName, grade ) { person.call(this, firstName, lastName); this.Averagegrade = grade; }; const group = function(Title, firstName,lastName, grade ) { this.Title = Title; person.call(this, firstName, lastName); student.call(this, grade); const addstudent = Object.create(person); return firstName + ' ' + lastName ; }; group.__proto__ = student; const john = new student('Jack','Sparrow', '53'); john.setFullName('Jack', 'Sparrow'); const group1 = new group( "group1"); group1.addstudent(john); console.log(group1);

pero sigo obteniendo esto como salida

 group { Title: 'group1', firstName: undefined, LastName: undefined, getFullName: [Function (anonymous)], setFullName: [Function (anonymous)], Averagegrade: undefined }