极湖

(function($){
    /**
     * Get selected option's property
     */
    $.fn.getSelectedProperty = function(property) {
        var arrValue = Array();
        var a=0;
        this.each( function() {
            for (var i=0; i < this.options.length; i++) {
                if (this.options[i].selected == true) {
                    arrValue[a] = this.options[i][property]; 
                    a++;
                }
            }
        });
    
        if(arrValue.length > 1) {
            return arrValue;
        } else if(arrValue.length == 1) {
            return arrValue[0];
        }
        return '';
    };
})(jQuery);

alert($("#select_box_id").getSelectedProperty('text'));