changeImage = function(img) {

	document.getElementById("main").src = img;

}
changeImage2 = function(target, img) {

	document.getElementById("main").src = img;

	var switchbtns = document.getElementsByClassName('switchbtn');
	var switchbtns_number = switchbtns.length;
	for (var i = 0; i < switchbtns_number; i++) {
		switchbtns[i].src.match(/\.\w+$/);
		var ext = RegExp.lastMatch;
		var tmp = switchbtns[i].src.replace(ext, '');
		if (tmp.match(/_now$/)) {
			switchbtns[i].src = tmp.replace(/_now$/, '') + ext;
		}
	}

	var childs = $(target).childNodes;
	var img_src = childs[0].src;
	img_src.match(/\.\w+$/);
	var ext = RegExp.lastMatch;
	var tmp = img_src.replace(ext, '');
	if (!tmp.match(/_now$/)) {
		childs[0].src = tmp + '_now' + ext;
	}

}