selectedIndex method is showing the right alert but i am not getting the value back. I get the jquery object back. How can i change it so that i get the value back for the selectedIndex method?

Code:
jQuery.fn.dropdownHelper = function(method) {
    var methods = {
        init: function(){ },
        empty: function(){
            if (this.tagName == 'SELECT')
                this.options.length = 0;
        },
        selectedIndex: function(){
            var index = this.selectedIndex;    
            if(index == 'undefined')
                index = -1;
            alert (index);
            return index;    
        }
    };
    return this.each(function() {     
        // Method calling logic
        if ( methods[method] )
              return methods[ method ].apply( this, Array.prototype.slice.call( arguments, 1 ));
        else if ( typeof method === 'object' || ! method )
              return methods.init.apply( this, arguments );
        else
              $.error( 'Method ' +  method + ' does not exist' );
    });
};