// 画像の名前の最後に_offと_onを付けるだけで
// 自動的にロールオーバーを実装するJavaScript

function smartRollover() {  
  if(document.getElementsByTagName) {  
    var tags = ["img","input"];  
    var len = tags.length;  
    for( var i=0; i<len; i++ ) {  
      var el = document.getElementsByTagName(tags[i]);  
      var len2 = el.length;  
      for(var j=0; j<len2; j++) {  
        var attr = el[j].getAttribute("src");  
        if( attr ) {  
          if(el[j].getAttribute("src").match(/_off\./))  
          {  
            el[j].onmouseover = function() {  
              this.setAttribute("src", this.getAttribute("src").replace("_off.", "_on."));  
            }  
            el[j].onmouseout = function() {  
              this.setAttribute("src", this.getAttribute("src").replace("_on.", "_off."));  
            }  
          }  
        }  
      }  
    }  
  }  
}  
if(window.addEventListener) {  
  window.addEventListener("load", smartRollover, false);  
}  
else if(window.attachEvent) {  
  window.attachEvent("onload", smartRollover);  
}