属性继承

function Person(name,age){
  this.name = name;
  this.age = age;
}/构造函数中this指向实例对象/
function Teacher(name,age,skill){
  // var self = this;
  Person.call(self,name,age)
  this.skill = skill;
}
var t = new Teacher("zhang",18,"js");
console.log(t)

方法继承

function Person(name,age){
  this.name = name;
  this.age = age;
}
Person.prototype.sayName = function(){
  console.log(this.name)
}
function Teacher(name,age,skill){
  Person.call(this,name,age)
  this.skill = skill;
}
Teacher.prototype = Person.prototype;//将地址值传给了Teacher的prototype，这样就继承了Person的方法
Teacher.prototype.sayAge = function(){
  console.log(this.age)
}
//未赋值之前Teacher的prototype的地址是Person的prototype地址，现在用Teacher覆盖
Teacher.prototype.constructor =  Teacher;
var t = new Teacher("zhang",18,"js");
var p = new Person("lisi",13);
console.log(t)
console.log(t.constructor)

class类的继承

class Person{
  constructor(name,age) {
    this.name = name;
    this.age = age;                
  }
  sayName(){
    console.log(this.name)
  }
}
class Teacher extends Person {
  /* 类继承之后,构造函数第一行必须写super关键字 去继承父类的属性*/
  constructor(name,age,skill){
    super(name,age);
    this.skill = skill;
  }
  /* 在子类的方法中调用父类的方法 可以通过this或super去调用 */
  show(){
    this.sayName();
    // super.sayName();
  }
}
var t = new Teacher("zhang",18,"js");
console.log(t)

静态属性,静态方法

属于类所独有的
特点:通过类名去调用

class Person{
  constructor(name,age){
    this.name = name;
    this.age = age;
  }
  static sayName(){
    console.log("name")
  }
}
var p = new Person("lisi",19);
Person.sayName()

静态方法:
1.静态方法是属于类所独有的,类创建的时候,就会在内存中存在。不用实例化,直接通过类名直接调用,不会造成系统资源的格外浪费
2.不可以在静态方法中,调用普通方法
3.静态方法中的this,指调用静态方法的这个类
4.静态方法是可以被继承的
在静态方法中this指—>调用静态方法的类

class Person{
  constructor(name,age){
    this.name = name;
    this.age = age;
  }
  sayAge(){
    Person.sayName();
    console.log(this.age);
  }
  static sayName(){
    // this.sayAge();添加此句则报错
    console.log("name")
  }
}
var p = new Person("name",18)
Person.sayName();
p.sayAge();

1.子类可以继承父类的静态方法
2.在子类的静态方法中调用父类的静态方法,可以通过super/this去调用

class Person{
  static baseUrl = "https://www.baidu.com"
static sayName(){
  console.log("name")
}
}
class Teacher extends Person{
  static sayAge(){
    super.sayName();
    console.log(super.baseUrl)
    console.log("age");
  }
}
Teacher.sayAge()
console.log(Teacher.baseUrl)