JavaScript 继承机制详解：从原型链到类式继承的演进

<script type="text/javascript"> 


  function Person(name, age) 
  { 
   this.name = name; 
   this.age = age; 
  } 
  Person.prototype.say = function () 
  { 
   console.log(this.name + " , " + this.age); 
  } 
  function Student(no) 
  { 
   this.no = no; 
  } 
  /** 
   * Student的prototype指向Person的对象 
   */</span> 
  Student.prototype = new Person(); 
  var stu1 = new Student("0001"); 
  stu1.name = '张三'; 
  stu1.age = '11'; 
  console.log(stu1.no); 
  stu1.say(); 
 </script> 

<script type="text/javascript"> 
  /** 
  * 存在问题 
  * 1、无法在Student的构造方法中传递参数用于父类的构造方法 
  * 2、对于引用类型变量，造成数据不一致 
  */ 


  function Person(name, age) 
  { 
   this.name = name; 
   this.age = age; 
   this.hobbies = [] ; 
  } 
  Person.prototype.say = function () 
  { 
   console.log(this.name + " , " + this.age +" , " +this.hobbies); 
  } 
  function Student(no) 
  { 
   this.no = no; 
  } 
  Student.prototype = new Person(); 

  var stu1 = new Student("0001"); 
  stu1.name = '张三'; 
  stu1.age = '11'; 
  stu1.hobbies.push("soccer"); 
  stu1.say(); 

  var stu2 = new Student("0002"); 
  stu2.name = '李四'; 
  stu2.age = '12'; 
  stu2.hobbies.push("girl"); 
  stu2.say(); 
 </script> 

<script type="text/javascript"> 

  function Person(name, age) 
  { 
   this.name = name; 
   this.age = age; 
   this.hobbies = []; 
  } 
  Person.prototype.say = function () 
  { 
   console.log(this.name + " , " + this.age +" , " + this.hobbies); 
  } 

  function Student(name, age, no) 
  { 
   /** 
   * 使用call方法，第一个参数为上下文； 
   * 有点类似Java中的super(name,age)的感觉 
   */ 
   Person.call(this, name, age); 
   this.no = no; 
  } 

  Student.prototype = new Person(); 

  var stu1 = new Student("0001","张三",11); 
  stu1.hobbies.push("soccer"); 
  stu1.say(); 

  var stu2 = new Student("0002","李四",12); 
  stu2.hobbies.push("cangjin"); 
  stu2.hobbies.push("basketball"); 
  stu2.say(); 
 </script> 

<script type="text/javascript"> 

 /** 
  * 基于原型链的集成中都是对象 
  * 存在问题： 
  * 1、对于引用类型变量，造成数据不一致 
  */ 
 var Person = { 
    name: "人", 
    age: 0, 
    hobbies: [], 
    say: function () 
    { 
     console.log(this.name + " , " + this.age + " , " + this.hobbies); 
    } 
   } 
   ; 

 var Student = clone(Person); 
 Student.no =""; 
 Student.sayHello = function() 
 { 
  console.log(this.name +"hello ") ; 
 } 

 var stu1 = clone(Student); 
 stu1.name = "zhangsan"; 
 stu1.age = 12; 
 stu1.hobbies.push("Java"); 
 stu1.say(); 

 var stu2 = clone(Student); 
 stu2.name = "lisi"; 
 stu2.age = 13; 
 stu2.hobbies.push("Javascript"); 
 stu2.say(); 

 /** 
  * 返回一个prototype执行obj的一个对象 
  * @param obj 
  * @returns {F} 
  */ 
 function clone(obj) 
 { 
  var F = function () 
  { 
  }; 
  F.prototype = obj; 
  return new F(); 

 } 
</script>