Access modifiers

So far, all our class properties and methods have automatically had the public access modifier. This means they are available to interact with class instances and child classes. We can explicitly set the public keyword on our class properties and methods immediately before the property or method name:

class OrderDetail {
  public product: Product;
  public quantity: number;

  public getTotal(discount: number): number {
    const priceWithoutDiscount = this.product.unitPrice * this.quantity;
    const discountAmount = priceWithoutDiscount * discount;
    return priceWithoutDiscount - discountAmount;
  }
}

As you might have guessed, there is another access modifier, called private, which allows the member to only be available to interact with inside the class and not on class instances or child classes.

Let's look at an example:

1. Let's add a delete method in our OrderDetail class, which sets a private deleted property:

class OrderDetail {
  public product: Product;
  public quantity: number;
  private deleted: boolean;

  public delete(): void {
    this.deleted = true;
  }
  ...
}

1. Let's create an instance of OrderDetail and try to access the deleted property:

const orderDetail = new OrderDetail();
orderDetail.deleted = true;

As expected, the compiler complains:

There is a third access modifier, protected, which allows the member to be available to interact with inside the class and on child classes, but not on class instances.