es6中的class类

es6中的class类

class Person {
        constructor (name, age) {
          this.name = name
          this.age = age
        }
        eat () {
          alert(`${this.name} eat something`)
        }
        speak () {
          alert(`My name is ${this.name},age ${this.age}`)
        }
      }
      let zhang = new Person('zhang', 20)
      zhang.eat()
      zhang.speak()
      let wang = new Person('wang', 34)
      wang.eat()
      wang.speak()
    }

继承

class Student extends Person {
        constructor (name, age, number) {
          super(name, age)
          this.number = number
        }
        study () {
          alert(`${this.name} study`)
        }
      }
      let xiaoming = new Student('xiaoming', 10, 'A1')
      xiaoming.study()
      console.log(xiaoming.number)
      xiaoming.eat()
      let xiaohong = new Student('xiaohong', 11, 'A2')
      xiaohong.study()
      xiaohong.speak()

People是父类 公共的 不仅仅服务于Student
继承可将公共方法抽离出来，提高复用，减少冗余

封装

public完全开放
protected 对子类开放
private 对自己开放
ES6尚不支持，可以用typescript来演示

 class Person {
        name
        age
        protected weight //定义protected属性  只有自己和子类可访问
        constructor (name, age) {
          this.name = name
          this.age = age
          this.weight = 120
        }
        eat () {
          alert(`${this.name} eat something`)
        }
        speak () {
          alert(`My name is ${this.name},age ${this.age}`)
        }
      }
      class Student extends Person {
        number
        private girlfriend //定义private屬性
        constructor (name, age, number) {
          super(name, age)
          this.number = number
          this.girlfriend = 'xiaoli'
        }
        study () {
          alert(`${this.name} study`)
        }
        getWeight(){
          alert (`${this.weight}`)
        }
         getFriend(){
          alert (`${this.girlfriend}`)
        }
      }
      let xiaoming = new Student('xiaoming', 10, 'A1')
      xiaoming.study()
      xiaoming.getWeight()
    //   alert(xiaoming.girlfriend) //会报错，只能自己内部使用
      xiaoming.eat()
     xiaoming.getFriend()
      // let xiaohong = new Student('xiaohong', 11, 'A2')
      // xiaohong.study()
      // xiaohong.speak()