es6 logging function are undefined

Question

I am trying to figure out why i cannot call methods i have set in my classes. I have a class in es6

class school {
  constructor(size = '10', subjects = {
    math: 'green',
    physics: 'green',
    language: 'orange',
    history: null
  }) {
    this.size = size;
    this.subjects = subjects;
    this.classCode = null;
  }

  changeSubject(study) {
    this.classCode = this.subjects[study];
    if (study === 'math') {
      this.size += 1;
    }
  }
}

class room extends school {
  constructor(roomQty = 15, size, subjects) {
    super(size, subjects);
    this.roomQty = roomQty;
  }

  changeStudy(study) {
    super.changeStudy(study);
    if (study === 'math') {
      this.roomQty += 1;
    }
  }

  gatherStudents() {
    this.roomQty -= 3;
  }
}

const myRoom = new room(10, 4);

When I log this using console.log, I get an undefined message.

console.log(myRoom.changeStudy('language'));
console.log(myRoom.gatherStudents());
console.log(myRoom.changeStudy('math'));

How can i call these function and print the results to the console.

Answer 1

There were several problems with your code. The main problem was that your methods do not return anything and that your "super" Class did not implement the referenced method:

 class school { constructor(size = '10', subjects = {math: 'green', physics: 'green', language: 'orange', history: null}) { this.size = size; this.subjects = subjects; this.classCode = null; this.study = null } changeStudy(study) { this.study = study } changeSubject(study) { this.classCode = this.subjects[study]; if (super.study === 'math') { this.size += 1; } } } class room extends school { constructor(roomQty = 15, size, subjects) { super(size, subjects); this.roomQty = roomQty; } changeStudy(study) { super.changeStudy(study); if (this.study === 'math') { return this.roomQty += 1; } else { return 0 } } gatherStudents() { return this.roomQty; } } const myRoom = new room(10,4); console.log(myRoom.changeStudy('language')); console.log(myRoom.gatherStudents()); console.log(myRoom.changeStudy('math'));