Classi e costruttori in TypeScript

Benvenuto

Dichiarazione di una classe con proprietà

class Person {
  name: string;
  age: number;

  constructor(name: string, age: number) {
    this.name = name;
    this.age = age;
  }
}

Sintassi abbreviata delle proprietà nei parametri

class Person {
  constructor(
    public name: string,
    private age: number
  ) {} // properties created automatically
}

Metodi tipizzati

class Calculator {
  add(a: number, b: number): number {
    return a + b;
  }
}

Getter e setter

class Circle {
  constructor(private radius: number) {}
  get area(): number { return Math.PI * this.radius ** 2; }
  set r(v: number) { this.radius = v; }
}

La classe come tipo

class Dog { name = 'Rex'; bark() { return 'Woof'; } }
const d: Dog = new Dog();

Membri statici

class MathHelper {
  static PI = 3.14159;
  static square(n: number): number { return n * n; }
}
console.log(MathHelper.PI);

Ereditarietà delle classi

class Animal {
  constructor(public name: string) {}
  speak(): string { return '...'; }
}
class Dog extends Animal {
  speak(): string { return 'Woof!'; }
}

Classi astratte

abstract class Shape {
  abstract area(): number;
  describe(): string { return `Area: ${this.area()}`; }
}
class Square extends Shape {
  constructor(private side: number) { super(); }
  area() { return this.side ** 2; }
}

Il tipo this nelle classi

class Builder {
  private parts: string[] = [];
  add(p: string): this { this.parts.push(p); return this; }
  build(): string { return this.parts.join(','); }
}

Classe, interface e type

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