面向对象三要素

继承

子类继承父类

class People {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
  eat() {
    console.log(`${this.name} eat something`);
  }
  speak() {
    console.log(`my name is ${this.name}, age ${this.age}`);
  }
}

class Student extends People {
  constructor(name, age, number) {
    super(name, age);
    this.number = number;
  }
  study() {
    console.log(`${this.name} study`);
  }
}

const olu = new Student("olu", 3, "A1");
olu.eat();
olu.speak();
olu.study();

封装

数据的权限和保密

• public 完全开放
• protected 对子类开放
• private 对自己开放

class People {
  name;
  age;
  protected weight;
  constructor(name, age) {
    this.name = name;
    this.age = age;
    this.weight = 250;
  }
  eat() {
    console.log(`${this.name} eat something`);
  }
  speak() {
    console.log(`my name is ${this.name}, age ${this.age}`);
  }
}

class Student extends People {
  number;
  private lover;
  constructor(name, age, number) {
    super(name, age);
    this.number = number;
    this.lover = "olu";
  }
  study() {
    console.log(`${this.name} study`);
  }
  getWeight() {
    console.log(`${this.weight}`);
  }
}

const olu = new Student("olu", 3, "A1");
olu.eat();
olu.speak();
olu.getWeight();

多态

同一接口不同实现

class People {
  constructor(name) {
    this.name = name;
  }
  printName() {
    console.log(`my name is ${this.name}`);
  }
}

class Student extends People {
  constructor(name) {
    super(name);
  }
  printName() {
    console.log(`student name is ${this.name}`);
  }
}

class Worker extends People {
  constructor(name) {
    super(name);
  }
  printName() {
    console.log(`worker name is ${this.name}`);
  }
}

const olu = new Worker("olu");
olu.printName();