Class object overlapping

Question

im still trying to learn and im trying to make a group of actors be added to a movie class, i made it work but i still have problems because if you add another actor the last one dissappears, i tried with a loop but i could do nothing.

class Movie {
    constructor(title,year,duration){
        this.title = title;
        this.year = year;
        this.duration = duration;
    }

    addCast(actors){
        this.actors = actors
    }
}     
class Actor {
    constructor(name,age)
    {  
        this.name = name;
        this.age = age;
    }
}

const terminator = new Movie('Terminator I', 1985, 60);
const arnold = new Actor('Arnold Schwarzenegger', 50);
const otherCast = [
    new Actor('Paul Winfield', 50),
    new Actor('Michael Biehn', 50),
    new Actor('Linda Hamilton', 50)
];
//From here it can not be modified
    let movieOne = new Movie("Kong","2018","2h30m");
    let movieTwo = new Movie("Joker","2019","2h03m");
    let movieThree = new Movie("John Wick 3", "2019", "1h49m");
    terminator.addCast(arnold);
    terminator.addCast(otherCast);
//To here it can not be modified
    console.log({movieOne,movieTwo,movieThree,terminator});

See? Arnold should be in the actors too but it isnt! Thanks for the help in advance.

Another thing, this is for an excercise and i can not modify the lines i commented.

Answer 1

You have

addCast(actors){
    this.actors = actors
}

This does not add the passed actor array to the actors on the instance - it replaces the instance's actors with the passed argument. Calling addCast will result in whatever previously existed on actors being lost.

To help reduce bugs, it can help to name methods appropriately - for logic like this, I'd call it setCast, not addCast.

If you want to add onto the end of the existing cast, and you're not sure whether the argument will be a single actor to add or an array of actors to add, use:

  addCast(actorOrActors) {
    if (Array.isArray(actorOrActors)) {
      this.actors.push(...actorOrActors);
    } else {
      this.actors.push(actorOrActors);
    }
  }

class Movie {
  constructor(title, year, duration) {
    this.title = title;
    this.year = year;
    this.duration = duration;
    this.actors = [];
  }

  addCast(actorOrActors) {
    if (Array.isArray(actorOrActors)) {
      this.actors.push(...actorOrActors);
    } else {
      this.actors.push(actorOrActors);
    }
  }
}
class Actor {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
}

const terminator = new Movie('Terminator I', 1985, 60);
const arnold = new Actor('Arnold Schwarzenegger', 50);
const otherCast = [
  new Actor('Paul Winfield', 50),
  new Actor('Michael Biehn', 50),
  new Actor('Linda Hamilton', 50)
];
//From here it can not be modified
let movieOne = new Movie("Kong", "2018", "2h30m");
let movieTwo = new Movie("Joker", "2019", "2h03m");
let movieThree = new Movie("John Wick 3", "2019", "1h49m");
terminator.addCast(arnold);
terminator.addCast(otherCast);
//To here it can not be modified
console.log({
  movieOne,
  movieTwo,
  movieThree,
  terminator
});