getters-setters.md

In TypeScript, getters and setters are special methods that provide read and write access to an object's properties. They are a part of the ES5 standard and are fully supported in TypeScript.

Getters are methods that get the value of a specific property. Setters are methods that set the value of a specific property.

class MyClass {
  private _myProp: string;

  get myProp(): string {
    return this._myProp;
  }

  set myProp(value: string) {
    if (!value) {
      throw new Error('Invalid value!');
    }
    this._myProp = value;
  }
}

let instance = new MyClass();
instance.myProp = 'Hello, world'; // OK
console.log(instance.myProp); // "Hello, world"

In this example, myProp is a property with a getter and a setter. The getter returns the value of _myProp, and the setter validates the new value before setting _myProp.

Use Cases:

1. Validation: You can use setters to validate the data before setting a property. This ensures that your object is always in a valid state.

2. Encapsulation: Getters and setters provide a way to encapsulate the internal representation of an object's data. This allows you to change how the data is stored internally without affecting code that uses the object.

3. Computed Properties: You can use getters to create computed properties that are calculated based on other properties.

class Rectangle {
  constructor(public width: number, public height: number) { }

  get area(): number {
    return this.width * this.height;
  }
}

let rect = new Rectangle(5, 10);
console.log(rect.area); // 50

In this example, area is a computed property that calculates the area of the rectangle based on its width and height.