Javascript: Extendible Pattern

pattern.js

//Self-Executing Anonymous Func: Part 2 (Public & Private)
(function( skillet, $, undefined ) {
    //Private Property
    var isHot = true;
 
    //Public Property
    skillet.ingredient = "Bacon Strips";
     
    //Public Method
    skillet.fry = function() {
        var oliveOil;
         
        addItem( "\t\n Butter \n\t" );
        addItem( oliveOil );
        console.log( "Frying " + skillet.ingredient );
    };
     
    //Private Method
    function addItem( item ) {
        if ( item !== undefined ) {
            console.log( "Adding " + $.trim(item) );
        }
    }    
}( window.skillet = window.skillet || {}, jQuery ));
 
//Public Properties
console.log( skillet.ingredient ); //Bacon Strips
 
//Public Methods
skillet.fry(); //Adding Butter & Fraying Bacon Strips
 
//Adding a Public Property
skillet.quantity = "12";
console.log( skillet.quantity ); //12
 
//Adding New Functionality to the Skillet
(function( skillet, $, undefined ) {
    //Private Property
    var amountOfGrease = "1 Cup";
     
    //Public Method
    skillet.toString = function() {
        console.log( skillet.quantity + " " + 
                     skillet.ingredient + " & " + 
                     amountOfGrease + " of Grease" );
        console.log( isHot ? "Hot" : "Cold" );
    };    
}( window.skillet = window.skillet || {}, jQuery ));
 
try {
    //12 Bacon Strips & 1 Cup of Grease
    skillet.toString(); //Throws Exception
} catch( e ) {
    console.log( e.message ); //isHot is not defined
}