构造函数模式

    function student(props){this.name=props.name || '匿名';//默认是匿名this.grade=props.grade || 1;}student.prototype.hello=function(){console.log('hello ' this.name);}function createStudent(props){return new student(props||{})}var xiaoming=createStudent({name:'xiaoming'});xiaoming.hello();//hello xiaoming

传进一个数组

    function animal(name,age,grade){this.name=name;this.age=age;this.grade=grade;}animal.prototype.hello=function(){console.log('hello ' this.name);}var chicken=new animal('chicken',3,12);chicken.hello();//hello chicken

我理解的构造函数就是用new()实例化去构造

看了原型继承，发现原型继承不了

所以就看代码

    function student(name){this.name=name||'unname';}student.prototype.hello=function(){console.log('hello' this.name)}function cat(grade){student.call(this,grade);this.grade=grade||12}var a=new cat()//a.name=unname,a.grade=12,a.hello() is not a function不可以继承student的原型，
    function f(){}f.prototype=student.prototype;cat.prototype=new f()var b=new cat();//b.name=unname,b.grade=12,b.hello()='hello unname'可以继承student的原型

通过call来调用继承，并绑定this

也可以用class来extends

class student{constructor(name){this.name=name}hello(){console.log('hello' this.name)}
}
class cat extends student{constructor(name,grade){super(name);this.grade=grade;}myGrade(){console.log('my grade is' this.grade)}
}
var a=new cat()
//a.name,a.hello(),a.grade,a.myGrade()都能用