构造函数
约定俗成：首字母大写；
function Dog(name,sex){
this.name = name;
this.sex = sex;
this.action = function(){
console.log("吃、叫、撒欢");
}
}
调用构造函数；
实例化；关键字：new(把抽象类具体化，把类变成对象);
var xiaohei = new Dog("小黑","female");
console.log(xiaohei.name);
xiaohei.action();
new 具体做了什么？三件事
1 . 创建另一个空的对象
var obj = {};
2 . 改变this指向：call aplly bind
Dog.call(obj,"小黑","female");
console.log(obj);
3 . 赋值原型
obj.__proto__ = Dog.prototype;
构造函数的原型
对象是由自身和原型共同构成的；构造函数的原型prototype，属性写在构造函数里，方法写在原型上
function Person(name,age,height){
this.name = name;
this.age = age;
this.height = height;
}
Person.prototype.action = function(){
//this指实例化的对象 实例化对象共用this
console.log(this);
console.log("姓名是："+this.name);
}
Person.prototype.hobby = function(){
console.log(this);
console.log("喜欢");
}
Person.prototype = function(){
action:function(){
console.log("run");
}
}
var newPerson = new Person("张三",19,"178cm");
prototype和proto对比，一个实例化之前，表现形式不同而已
console.log(Person.prototype === newPerson.__proto__); //true
通过原型找到构造函数 constructor
function Person(name){
this.name = name;
}
console.log(Person.prototype.constructor);
image.png
类
类的特性：封装 ，继承，多态，重载
function Person(name){
//私有属性；作用域
var name = name;
//共有属性；
this.height = "183cm";
//get方法，通过共有方法访问私有属性
this.get = function(){
return name;
}
//set方法：设置私有属性
this.set = function(newName){
name = newName;
console.log(name);//李四
}
}
var newPerson = new Person("张三");
console.log(newPerson.get());//张三
newPerson.set("李四");
继承 call apply bind
function Dad(height){
this.name = "张三";
this.age = 58;
this.height= height;
this.money = "$1000000";
this.hobby = function(){
console.log("喜欢太极");
}
}
function Son(height){
//继承的三种方法 call apply bind
Dad.call(this,height,money);
// Dad.apply(this,[height,money]);
// Dad.bind(this)(height,money);
this.action = function(){
console.log("wan");
}
}
var newSon = new Son("180cm");
console.log(newSon.height);
newSon.hobby();
newSon.action();
image.png
继承父类原型，涉及到传址问题，影响父级
Student.prototype = Person.prototype;
//重写子级的方法会影响父级
Student.prototype.hobby = function(){
console.log("我是重写方法");
}
解决传值问题
function Link(){};
Link.prototype = Person.prototype;
Student.prototype = new Link();
ES6 类
class Person{
//类最开始在加载的时候执行
constructor(name,age){
this.name = name;
this.age = age;
}
hobby(){
console.log("喜欢");
}
showName(){
console.log(this.name);
}
}
var zs = new Person("zs",28);
console.log(zs.age);
zs.showName();
//类的继承
class Student extends Person{
constructor(name,age){
//super传参，继承属性
super(name,age);
}
action(){
console.log("我是action函数");
}
}
var newStudent = new Student("李四",222);
console.log(newStudent.name);
newStudent.hobby();
