类

类

class Greeter {
  greeting: string
  constructor(message: string) {
    this.greeting = message
  }
  greet() {
    return `Hello,${this.greeting}`
  }
}
let greeter = new Greeter('world')

继承

class Animal {
  move(s: number = 0) {
    console.log(`Animal moved ${s}m.`);
  }
}
class Dog extends Animal {
  bark() {
    console.log('woof! woof!');
  }
}
const dog = new Dog()
dog.bark()
dog.move(10)
dog.bark()
class Animal {
  name: string;
  constructor(theName: string) { this.name = theName; }
  move(distanceInMeters: number = 0) {
    console.log(`${this.name} moved ${distanceInMeters}m.`);
  }
}
class Snake extends Animal {
  constructor(name: string) { super(name); }
  move(distanceInMeters = 5) {
    console.log("Slithering...");
    super.move(distanceInMeters);
  }
}
class Horse extends Animal {
  constructor(name: string) { super(name); }
  move(distanceInMeters = 45) {
    console.log("Galloping...");
    super.move(distanceInMeters);
  }
}
let sam = new Snake("Sammy the Python");
let tom: Animal = new Horse("Tommy the Palomino");
sam.move();
tom.move(34);
// Slithering...
// Sammy the Python moved 5m.
// Galloping...
// Tommy the Palomino moved 34m.
public    private  readonly
class Animal {
  private name: string
  public age: number
  readonly money: number
  constructor(theName: string) {
    this.name = theName
    this.age = 18
  }
}
class Rhino extends Animal {
  constructor() { super("Rhino"); }
}
class Employee {
  private name: string;
  constructor(theName: string) { this.name = theName; }
}
// new Animal('nn').name  //私有的无法访问
let animal = new Animal("Goat");
let rhino = new Rhino();
let employee = new Employee("Bob");
// animal.money = 100 // error 只读不能修改
animal = rhino;
// animal = employee; // 错误: Animal 与 Employee 不兼容.

protected 静态属性

class Person {
  protected name: string
  static color: string
  constructor(name: string) {
    this.name = name
  }
  greet(){
    return Person.color
  }
}
class Employee extends Person {
  private department: string
  constructor(name: string, department: string) {
    super(name)
    this.department = department
  }
  public getElevatorPitch() {
    return `my name is ${this.name} and I work in ${this.department}`
  }
}
let xiaoming = new Employee('xiaoming','shop')
console.log(xiaoming.getElevatorPitch());
// console.log(xiaoming.name); //属性“name”受保护，只能在类“Person”及其子类中访问。

把类当做接口使用

class Point {
  x: number;
  y: number;
}
interface Point3d extends Point {
  z: number;
}
let point3d: Point3d = { x: 1, y: 2, z: 3 };