jq(function() {
	set_rollovers(jq('#nav_main img:not(.on, .off)'));
});

// images preloader: params => strings || array
function preload_images() {
	var img  = jq('<img>'),
			args = typeof arguments[0] == 'object' ? arguments[0] : arguments;
	
	for ( var i = 0; i < args.length; i++ ) {
		var file = args[i].split('.');
		
		img.attr('src', file[0] + '_ro.' + file[1]);
	}
}

// set nav rollovers
function set_rollovers(images) {
	// img srcs w/o timestamp
	var srcs = images.map(function(){ return jq(this).attr('src').split('?')[0] });
	
	preload_images(srcs);
	for ( var i = 0; i < images.length; i++ )
		set_rollover(images[i]);
}

// set rollover handlers: params => <img>
function set_rollover(image) {
	jq(image).mouseover(function() {
		var self = jq(this),
				file = self.attr('src').split('?')[0];
		
		self.attr('src', file.replace('.', '_ro.'));
	}).mouseout(function() {
		var self = jq(this),
				file = self.attr('src').split('?')[0];
		
		self.attr('src', file.replace('_ro.', '.'));
	});
}