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Accepted
Mario López Batres
Asked: 2020-01-17 04:42:06 +0800 CST 2020-01-17 04:42:06 +0800 CST

Is it necessary to initialize an object in angular?

  • 772

I have an outer class export classas a template for an object.

export class Car{
  name: Boolean;
  other: {
    prize: String;
    brand: String;
  };
  doors: {
    number: String,
    size: String,
  };
}

I'm trying to access it from another class, so I've created a new variable

var car= new Car();

Since nameit is a boolean, I assume that it is initialized with a trueposition which is its default value. My problem comes when I try to initialize the object doorsafter it doesn't have it.

  var car= new Car();
  this.car.doors[pos].number;

When I try to access it it tells me that undefined. How could I access it? I guess I need to initialize it in the constructor.

I don't need to initializeother

javascript

1 Answers

  1. Best Answer

    You must initialize it in its constructor if you want to access its attributes, since it is an "Own Object" , here is an alternative:

     export class Car{
  name: Boolean;
  other: Others;
  doors: Doors;

 constructor(){
    this.name = (true / false); //Segun te parezca correcto.
    this.other = new Other(); // Inicializas el objeto Other - Opcional, ya que no lo necesitas
    this.doors = new Doors(); // Inicializas el objeto Doors
 }
}
// Alternativa a class Car ------------------------------------
export class Car {
  constructor(public name: Boolean = true,
              public doors: Doors = new Doors(), 
              public other: Other = new Other()){}

// Esto te permite tener un constructor al que le podrías pasar parámetros y si no lo haces por defecto utiliza lo que se encuentra a la derecha del =
//--------------------------------------------------------------
export class Doors{
    number: String;
    size: String;
}
export class Other {
    prize: String;
    brand: String;
}

    var car= new Car(); // Ya te permitiría ingresar a Doors y Others (si fuese necesario)

    The variables inside Otherand Doors, are going to be undefinedif you try to access them, since no value is assigned to them.

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