新建立的對像屬性值一樣

建立如下所示的javascript物件，並執行程式碼：

    function Person(name ,age ,sex ,weight){
    	this.name = name;
    	this.age = age;
    	this.sex = sex;
    	this.weight = weight;
    }
    Person.prototype.sayHi(){
    	console.log('你好');
    }
    function Student(score){
    	this.score = score;
    }
 

    Student.prototype = new Person('小明',10,'男','50kg');
    var stu1 = new Student(100);
    console.log(stu1.name,stu1.age,stu1.sex,stu1.weight,stu1.score);
    var stu2 = new Student(200);
    console.log(stu2.name,stu2.age,stu2.sex,stu2.weight,stu2.score);
    var stu3 = new Student(300);
    console.log
 
(stu3.name,stu3.age,stu3.sex,stu3.weight,stu3.score);

從執行結果，可以發現以下問題： 因為改變原型指向的同時實現繼承，直接初始化了屬性，繼承過來的屬性的值都是一樣的了，所以這就是問題。 解決方法：

function Person(name ,age ,sex ,weight){
     this.name = name;
     this.age = age;
     this.sex = sex;
     this.weight = weight;
}
Person.prototype.sayHi(){
     console.
 
log('你好');
}
function Student(name,age,sex,weight,score){
     //借用建構函式
     Person.call(this,name,age,sex,weight);
     this.score = score;
}
var stu1 = new Student('小明',20,'男','50kg',100);
console.log(stu1.name,stu1.age,stu1.sex,stu1.weight,stu1.score);
var stu2 = new Student('小紅',21,'女','45kg',90);
console.log(stu2.name,stu2.age,stu2.sex,stu2.weight,stu2.score);
var stu3 = new Student('小李',23,'男','60kg',98);
console.log(stu3.name,stu3.age,stu3.sex,stu3.weight,stu3.score);

可以發現，物件的屬性問題已經解決了，但是 person 物件的方法sayHi並沒由繼承過來。終極解決方案如（組合繼承）下

function Person(name ,age ,sex ,weight){
     this.name = name;
     this.age = age;
     this.sex = sex;
     this.weight = weight;
}
Person.prototype.sayHi(){
     console.log('你好');
}
function Student(name,age,sex,weight,score){
     //借用建構函式
     Person.call(this,name,age,sex,weight);
     this.score = score;
}
Student.prototype = new Person();
var stu1 = new Student('小明',20,'男','50kg',100);
console.log(stu1.name,stu1.age,stu1.sex,stu1.weight,stu1.score);
stu1.sayHi();
var stu2 = new Student('小紅',21,'女','45kg',90);
console.log(stu2.name,stu2.age,stu2.sex,stu2.weight,stu2.score);
stu2.sayHi();
var stu3 = new Student('小李',23,'男','60kg',98);
console.log(stu3.name,stu3.age,stu3.sex,stu3.weight,stu3.score);
stu3.sayHi();