https://www.rinka.co.jp/cmn/script/smartRollover.js

1(function(onLoad) {
2	try {
3		window.addEventListener('load', onLoad, false);
4	} catch (e) {
5		window.attachEvent('onload', onLoad);
6	}
7})(function() {
8	var tags = ["img","input"];
9	for( var i=0, len=tags.length; i<len; i++ ) {
10		var over = function() { this.src = this.src.replace('_off.', '_on.'); };
11		var out	= function() { this.src = this.src.replace('_on.', '_off.'); };
12		var el = document.getElementsByTagName(tags[i]);
13		for (var j=0, len2=el.length; j<len2; j++) {
14			var attr = el[j].getAttribute('src');
15			if (!el[j].src.match(/_off\./)&&attr) continue;
16			el[j].onmouseover = over;
17			el[j].onmouseout = out;
18		}
19	}
20});