在Jscript中定義類通過類聲明, 包含方法和對象和var 聲明。對于類的派生通過下面兩個程序的對比，你講清楚地明白。
    JScript 5.5 Code
// Simple object with no methods
function Car(make, color, year)
{
   this.make = make;
   this.color = color;
   this.year = year;
}
function Car.prototype.GetDescription()
{
   return this.year + " " + this.color + " " + this.make;
}
// Create and use a new Car object
var myCar = new Car("Accord", "Maroon", 1984);
print(myCar.GetDescription());
JScript.NET Code
// Wrap the function inside a class statement.
class Car
{
   var make : String;
   var color : String;
   var year : int;
   function Car(make, color, year)
   {
      this.make = make;
      this.color = color;
      this.year = year;
   }
   function GetDescription()
   {
      return this.year + " " + this.color + " " + this.make;
   }
}
var myCar = new Car("Accord", "Maroon", 1984);
print(myCar.GetDescription());
    Jscript.net還支持定義private和protected property通過GET和SET進行讀寫。
如下例：
class Person
{
   private var m_sName : String;
   private var m_iAge : int;
   function Person(name : String, age : int)
   {
      this.m_sName = name;
      this.m_iAge = age;
   }
   // Name 只讀
   function get Name() : String
   {
      return this.m_sName;
   }
   // Age 讀寫但是只能用SET
   function get Age() : int
   {
      return this.m_sAge;
   }
   function set Age(newAge : int)
   {
      if ((newAge >= 0) && (newAge <= 110))
         this.m_iAge = newAge;
      else
         throw newAge + " is not a realistic age!";
   }
}
var fred : Person = new Person("Fred", 25);
print(fred.Name);
print(fred.Age);
// 這將產生一個編譯錯誤，name是只讀的。
fred.Name = "Paul";
// 這個將正常執行
fred.Age = 26;
// 這將得到一個 run-time 錯誤, 值太大了
fred.Age = 200;