function MyObject(name, size) 
{ 
   this.name = name; 
   this.size = size; 
} 
MyObject.prototype.height = "2.26 meters"; 
MyObject.prototype.tellHeight = function() 
{ 
   return "height of "+this.name+" is "+this.height; 
} 
///使用 
var myobj1 = new MyObject("haha", 3); 
if (myobj1.tellHeight) 
{ 
   domDiv.innerHTML += myobj1.tellHeight()+"; 
}
http://www.cnblogs.com/lidabo/archive/2012/01/05/2313481.html