如何用Javascript写一个Class？

记得前面某次面试被问到此问题，一直以来因为对JS的不重视+一知半解，所以当时就懵了~

最近Google了下，找到以下几种写Class的方式：

1 JS因为不是OO语言，所以没有Class的概念，都是通过ProtoType的方式实现的。

var namedClass = Class.create({
    initialize: function(name) {
        this.name = name;
    }

    getName: function() {
        return this.name;
    }
});
var instance = new namedClass('Foobar');

2 也可以这样写

function MyClass(){
}
MyClass.prototype.aFunction(){
}

var instance = new MyClass();
instance.aFunction();

3 带属性和方法的Class

function MyClass () {
   //reference to this
   var self = this;
   //private member variable
   var privateVar = "My Private Variable";

   //public member variable
   this.publicVar = "My Public Variable";

   //private member function
   var privateFunction = function () {
      self.publicVar += " Modified By A Private Fucntion";
      alert( self.publicVar );
   }
}

//create an instance
var oClass = new MyClass();

//run a private member function
oClass.privateFunction();   //private function is undefined

//get a private member var
alert( oClass.privateVar );   //private var is undefined

4 带静态变量和静态方法的Class：

function MyClass () {
   //...
}
//declare a static member
MyClass.staticVar = "My static variable";

//declare a static function
MyClass.staticFunction = function ( pInput ) {
   return new MyClass( MyClass.staticVar , pInput );
}
//create an instance
var oClass = new MyClass();
//run a static function (NO access to private or public)
oClass.staticFunction( 9 );  //staticFunction is undefined on an instance
//run a privileged member function on the class
MyClass.privilegedFunction();   //The function runs

5 带特权(privileged)变量和方法的Class：

function MyClass () {
   //private member variable
   var privateVar = "My Private Variable";
   //privileged member function
   this.privilegedFunction = function () {
      alert( privateVar );
   }
}
//create an instance
var oClass = new MyClass();
//run a privileged member function
oClass.privilegedFunction();   //Output: alerts the value of the private var