javascript面向对象中继承实现的几种方式

1.原型链继承：

    function teacher(name){  
        this.name = name;  
    }  
    teacher.prototype.sayName = function(){  
        alert(this.name);
    }   
      
    function student(name){  
        this.name = name;  
    }  

    student.prototype = new teacher()  
    var student1 = new student("xiaolan");  
    student1.sayName();   
    //  name is xiaolan  

 2.组合式继承：

function Person  (name) {
             this.name = name;          
         };

         Person.prototype.getName = function () {
             return this.name;
         };

        function Parent (age) {
            Person.call(this,'老明');　　//这一步很关键
            this.age = age;
        };

        Parent.prototype = new Person('老明');　　//这一步也很关键
        var result = new Parent(24);
        console.log(result.name);　　　　//老明
        console.log(result.getName());　　//老明
        console.log(result.age);　　　　//24

        var result1 = new Parent(25);   //通过借用构造函数都有自己的属性，通过原型享用公共的方法
        console.log(result1.name);　　//老明