Question

note: for those SO fellow developers MS Ajax javascript library emulates classes, interface, enums and other OO features but the language does not support it. So don’t start bragging there isn’t a class in javascript.

Interface Implementation

/// <reference path="MicrosoftAjax.debug.js" />

Type.registerNamespace("Validators");

Validators.IValidate = function () {
    throw Error.notImplemented("Interface IValidate must be implemented before invoke.");
};

Validators.IValidate.prototype = {
    ErrorMessage: "",
    IsValid: false,
    Validate: function () {
        throw Error.notImplemented("Class must provide a implementation for the method");
    }
};
Validators.IValidate.registerInterface("Validators.IValidate");

Explanation:

Why am i explaining interface which doesn’t relate to the question? i will explain as it goes. The above code will create a Interface IValidate that mimics IValidator from the framework. The work of those Error.notImplemented code is as below

• Does not allow others to do this new Validators.IValidate() (i.e) no instance
• When a class implements the Interface, Validate() method will throw a error when not implemented

So now you must have understood how the emulation is performed. Similarly i created a class (actually i wanted a abstract class that’s why i am here), named BaseValidator like this

Validators.BaseValidator = function () {
    throw Error.invalidOperation("Base validator is a abstract class. Inherit the class to work with it");
};

Validators.BaseValidator.prototype = {
    ValidationProperty: function (propertyName) {
    },
    BackColor: function (hexCode) {
    },
    ControlToValidate: function (id) {
    },
    CssClass: function (css) {
    },
    Display: function (mode) {
    },
    Focus: function () {
    }
};

Validators.BaseValidator.registerClass("Validators.BaseValidator", null, Validators.IValidate);

at the last line you can notice that it implements Interface (but does not provide Implementation, because it will be provided by child classes of BaseValidator class). When ever a class implements Interface, inherits another class the constructor function should call Validators.BaseValidator.initializeBase(this) which would initialize base class. Now coming to the problem read carefully please

Problem

Validators.RequiredFieldValidator = function () {
    Validators.RequiredFieldValidator.initializeBase(this, []);
};
Validators.RequiredFieldValidator.prototype = {};
Validators.RequiredFieldValidator.registerClass("Validators.RequiredFieldValidator", Validators.BaseValidator);

• RequiredFieldValidator inherits BaseValidator as base class

• In the constructor calls the initializeBase(this) to initialize base class BUT
  Constructor in the BaseClass throws a error.

Question

How am i supposed to emulate a abstract class with Microsoft Asp.net Ajax

Answer 1

In the constructor calls the initializeBase(this) to initialize base class BUT Constructor in the BaseClass throws a error

Validators.RequiredFieldValidator = function () { };

What’s wrong with simply not calling the super constructor. If the constructor your inheriting from is meant to be abstract (a useless thing to do) then simply don’t ever call it.