(function($){
	$(function(){
		$.commonFunc.rollover();
	});
	$.commonFunc = {
		/**
		 * rollover
		 */
		rollover : function(options){
			var c = $.extend({
				selector:'.rollover',
				postfix: '_on'
			}, options);
			var image_cache = new Object();
			$(c.selector).each(function(i){
				var imgsrc = this.src;
				var dot = this.src.lastIndexOf(".");
				var imgsrc_on = this.src.substr(0, dot) + c.postfix + this.src.substr(dot, 4);
				image_cache[this.src] = new Image();
				image_cache[this.src].src = imgsrc_on;
				$(this).hover(
					function(){ this.src = imgsrc_on;},
					function(){ this.src = imgsrc;}
				);
			});
		}
	};
})(jQuery);