/*
	ロールオーバー処理本体。
*/

(function(autoRollover){	
		
	if(window.addEventListener) {
		window.addEventListener("load", autoRollover, false);
	} else if(window.attachEvent) {
		window.attachEvent("onload", autoRollover);
	} else {
		window.onload = autoRollover;
	}
	
})(function(){
	var roArray = getElementsByClassName('rollover');

	for(var i=0; i<roArray.length; i++){	
		roArray[i].onmouseover = function(){
			var s = this.src.split('\.');
			var ext = s[s.length-1];
			var regExp = new RegExp('\.'+ext+'$');

			this.src = this.src.replace(regExp, '_on\.'+ext);
		}
		
		roArray[i].onmouseout = function(){
			this.src = this.src.replace('_on\.', '\.');
		}
	}
});

/*
	class名を元に要素を取得する関数
*/

function getElementsByClassName(class_name, Container){
	var container = (Container == 'undefined') ? Container : document;
	var descendants = (container.all && !window.opera) ? container.all : container.getElementsByTagName('*');
	var elements = [];
	var regExp = new RegExp('\s?'+class_name+'\s?');
	for(var i=0; i<descendants.length; i++){
		if(descendants[i].className == class_name || descendants[i].className.match(regExp)){
			elements[elements.length] = descendants[i];
		}
	}
	
	return elements
}