JavaScript - Attempting To Understanding Privileged Methods And Object.create

/* This function will be used as a method inside the objects. */
function getPayment() {
    thePayment = 250;
    thePayment += (this.seats == 'leather') ? 100 : 50;
    thePayment += (this.engine == 'V-8') ? 150 : 75;
    thePayment += (this.radio == 'CD Player') ? 30 : 10;
    return thePayment;
}

/* Object Constructor (prototype of the object). */
function car(seats, engine, radio) {
    this.seats = seats;
    this.engine = engine;
    this.radio = radio;
    this.payments = getPayment; // No parenthesis.
}

/* Creates an instance called 'my_car' out of the 'car' object. */
var my_car = new car('cloth', 'V-6', 'Tape Deck');

/* Object Initializer - automatically instantiates the object. */
var carObj = {
     seats:  'leather',
     engine: 'V-8',
     radio:  'CD Player',
     payments: getPayment // No parenthesis. No comma after last item.
}

// Firebug...
console.log(my_car.payments()); // Parenthesis.
console.log(carObj.payments()); // Parenthesis.

/* vim:set foldmethod=indent: */

window.onload = initAll; // Why no () here?

function initAll() {
    window.doStuff(); // Why () here?
}

function doStuff() {

    var msg_text = 'I love you so much!';
    var msg_link = window.document.getElementById('msg_link');
    console.log(msg_link);
    var msg_box = window.document.getElementById('msg_box');

    msg_link.onmouseover = function() {
        //msg_box.value = msg_text;
        msg_box.setAttribute('value', 'May the force be with you!');
    };

    msg_link.onmouseout = function() {
        /* This works in ie. */
        //msg_box.value = '';

        /* Doesn't work in ie7 (and probably not in ie6 either).
         * Perhaps the code above is reasonable. */
        msg_box.removeAttribute('value');
    }
}
/* vim:set foldmethod=indent: */

renderfunction 	= false;

function showProperty (object, property)
{
	document.write  ('<td class="type">' + (typeof object[property])  + '</td>' 
					+ '<td class="name">' + property + '</td>');
	
	document.writeln('<td class="value">' + 
						(
								(typeof object[property] != 'function')
								? object[property]
								:(
										(property != 'showProperties')
										? (
											renderfunction
											? object[property]()
											: ('<span class="self">NOT RENDERED</span>')
											)
										: ('<span class="self">THIS</span>')
								 )
						) 
					+ '</td>');

	
	document.writeln('<td class="hasOwnProperty" >'  
							+ (
									object.hasOwnProperty(property)
									? "Local"
									: "Inherited"
								)
					 	+ '</td>');

	if (typeof object[property] == 'function')
	{
		document.writeln ('<td class="function">' + object[property] + '</td>');
	}
	else
	{
		document.writeln ('<td class="function"> </td>');
	}

}

(function($) {
    /*
    Validation Singleton
    */
    var Validation = function() {
        
        var rules = {
            
            email : {
               check: function(value) {
                   
                   if(value)
                       return testPattern(value,".+@.+\..+");
                   return true;
               },
               msg : "Enter a valid e-mail address."
            },
            url : {

               check : function(value) {

                   if(value)
                       return testPattern(value,"https?://(.+\.)+.{2,4}(/.*)?");
                   return true;
               },
               msg : "Enter a valid URL."
            },
            required : {
                
               check: function(value) {

                   if(value)
                       return true;
                   else
                       return false;
               },
               msg : "This field is required."
            }
        }
        var testPattern = function(value, pattern) {

            var regExp = new RegExp("^"+pattern+"$","");
            return regExp.test(value);
        }
        return {
            
            addRule : function(name, rule) {

                rules[name] = rule;
            },
            getRule : function(name) {

                return rules[name];
            }
        }
    }
    
    /* 
    Form factory 
    */
    var Form = function(form) {
        
        var fields = [];
    
        $(form[0].elements).each(function() {
            var field = $(this);
            if(field.attr('validation') !== undefined) {
                fields.push(new Field(field));
            }
        });
        this.fields = fields;
    }
    Form.prototype = {
        validate : function() {

            for(field in this.fields) {
                
                this.fields[field].validate();
            }
        },
        isValid : function() {
            
            for(field in this.fields) {
                
                if(!this.fields[field].valid) {
            
                    this.fields[field].field.focus();
                    return false;
                }
            }
            return true;
        }
    }
    
    /* 
    Field factory 
    */
    var Field = function(field) {

        this.field = field;
        this.valid = false;
        this.attach("change");
    }
    Field.prototype = {
        
        attach : function(event) {
        
            var obj = this;
            if(event == "change") {
                obj.field.bind("change",function() {
                    return obj.validate();
                });
            }
            if(event == "keyup") {
                obj.field.bind("keyup",function(e) {
                    return obj.validate();
                });
            }
        },
        validate : function() {
            
            var obj = this,
                field = obj.field,
                errorClass = "errorlist",
                errorlist = $(document.createElement("ul")).addClass(errorClass),
                types = field.attr("validation").split(" "),
                container = field.parent(),
                errors = []; 
            
            field.next(".errorlist").remove();
            for (var type in types) {

                var rule = $.Validation.getRule(types[type]);
                if(!rule.check(field.val())) {

                    container.addClass("error");
                    errors.push(rule.msg);
                }
            }
            if(errors.length) {

                obj.field.unbind("keyup")
                obj.attach("keyup");
                field.after(errorlist.empty());
                for(error in errors) {
                
                    errorlist.append("<li>"+ errors[error] +"</li>");        
                }
                obj.valid = false;
            } 
            else {
                errorlist.remove();
                container.removeClass("error");
                obj.valid = true;
            }
        }
    }
    
    /*
    Validation extends jQuery prototype
    */
    $.extend($.fn, {
        
        validation : function() {
            
            var validator = new Form($(this));
            $.data($(this)[0], 'validator', validator);
            
            $(this).bind("submit", function(e) {
                validator.validate();
                if(!validator.isValid()) {
                    e.preventDefault();
                }
            });
        },
        validate : function() {
            
            var validator = $.data($(this)[0], 'validator');
            validator.validate();
            return validator.isValid();
            
        }
    });
    $.Validation = new Validation();
})(jQuery);