6.继承

Javascript的继承是基于原型的继承

1-1 属性的继承

# call 实现属性的继承

function Person(name,age){
  this.name = name;   
  this.age = age
}
function Teacher(name,age,skill){
  Person.call(this,name,age)  // Person(name,age)中的this指向window,需要改变this指向
  this.skill = skill   // this指向 Teacher构造函数的实例对象
}
 var t = new Teacher("zhang",18,"js")
 console.log(t);

1-2 方法的继承

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;
+Teacher.prototype.constructor = Teacher;
Teacher.prototype.sayAge = function(){    
  console.log(this.age);  
}
var t = new Teacher("zhang",18,"js")
console.log(t);
+t.sayName()
t.sayAge()

1-2-1 es5中实现继承的方法

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 = Object.create(Person.prototype,{
  constructor:{
    value:Teacher
  }
})
Teacher.prototype.sayAge = function(){    
  console.log(this.age);  
}
var t = new Teacher("zhang",18,"js")
console.log(t);
console.log(t.constructor);
t.sayName()
t.sayAge()