Register namespace, and class

        <pre data-sub="prettyprint:_">
        Type.registerNamespace("Demo");

        Demo.Person = function(firstName, lastName, emailAddress) {
        this._firstName = firstName;
        this._lastName = lastName;
        this._emailAddress = emailAddress;
        }

        Demo.Person.prototype = {

        getFirstName: function() {
        return this._firstName;
        },

        getLastName: function() {
        return this._lastName;
        },

        getName: function() {
        return this._firstName + ' ' + this._lastName;
        },

        dispose: function() {
        alert('bye ' + this.getName());
        }
        }
        Demo.Person.registerClass('Demo.Person', null, Sys.IDisposable);

        // Notify ScriptManager that this is the end of the script.
        if (typeof(Sys) !== 'undefined') Sys.Application.notifyScriptLoaded();

        </pre>