//基于原型的继承
/*function Foo(){
this.y =2;
}
typeof Foo.prototype;//"object"
Foo.prototype.x = 1;
var obj = new Foo();
console.log(obj.x); //1
console.log(obj.y); //2*/
/*function Person(name,age){
this.name = name;
this.age = age;
}
Person.prototype.hi = function(){
console.log("Hi,my name is"+ this.name+", I am"+this.age+" years old now.");
};
Person.prototype.legs_num = 2;
Person.prototype.arms_num = 2;
Person.prototype.walk =function(){
console.log(this.name +"is walking...");
};
function Student(name,age,className){
Person.call(this,name,age);
this.className = className;
}
Student.prototype = Object.create(Person.prototype);
Student.prototype.constructor = Student;
Student.prototype.hi = function(){
console.log("Hi,my name is " +this.name+", I am" +this.age +" years old now,and from " +this.className +".");
}
Student.prototype.learn = function(subject){
console.log(this.name +" is learning " +subject+" at " +this.className +".");
}
var born = new Student('Bosn',23,'Class3');
born.hi();//Hi,my name is Bosn, I am23 years old now,and from Class3.
born.learn('English');//Bosn is learning English at Class3.
born.legs_num;
born.walk();//Bosnis walking...
Student.prototype.x =11;//赋值、添加时 影响已经实例过的对象
console.log(born.x);//11
Student.prototype={y:2};//直接修改赋值为新的对象时 对已经实例化过的对象没有影响,但是会影响 后续创建的实例 如下面的sunny
console.log(born.y);//undefined
console.log(born.x);//11
var sunny = new Student('sunny',3,'Class lol');//再次实例一个新的对象
console.log(sunny.x);//undefined
console.log(sunny.y);//2*/
![7M1J1U}$$N{]$@K(ENJY`YN.png](http://upload-images.jianshu.io/upload_images/3167851-bc45bbd891271ce4.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)
实现继承的方法:
OOP模拟重载
function Person(){
var args = arguments;
if(typeof args[0] ==='object' && args[0]){//防止参数为null 对象
if(args[0].name){
this.name = args[0].name;
}
if(args[0].age){
this.age = args[0].age;
}
}else{
if(args[0]){
this.name = args[0];
}
if(args[1]){
this.age = args[1];
}
}
}
Person.prototype.toString = function(){
return 'name ='+this.name+',age='+this.age;
}
var born = new Person('Born',23);
console.log(born.toString());//name =Born,age=23
var sunny = new Person({name:'Sunny',age:32});
console.log(sunny.toString());//name =Sunny,age=32