/**
 * 画像のロールオーバー処理
 */
function smartRollover()
{
    if (document.getElementsByTagName) {
        var i;
        var images = document.getElementsByTagName('img');
        
        for (i = 0; i < images.length; i++) {
            if (images[i].getAttribute('src').match(/_off\./)) {
                images[i].onmouseover = function() {
                    this.setAttribute('src', this.getAttribute('src').replace('_off.', '_on.'));
                }
                
                images[i].onmouseout = function() {
                    this.setAttribute('src', this.getAttribute('src').replace('_on.', '_off.'));
                }
            }
        }
    }
}

/**
 * prototype.jsより高速なgetElementsByClassName
 */
document.getElementsByClassName = function (className) {
    var i, j, eltClass;
    var objAll = document.getElementsByTagName ? document.getElementsByTagName('*') : document.all;
    var objCN = new Array();
    
    for (i = 0; i < objAll.length; i++) {
        eltClass = objAll[i].className.split(/\s+/);
        for (j = 0; j < eltClass.length; j++) {
            if (eltClass[j] == className) {
                objCN.push(objAll[i]);
                break;
            }
        }
    }
    
    return objCN;
}

if (window.addEventListener) {
    window.addEventListener('load', smartRollover, false);
} else if (window.attachEvent) {
    window.attachEvent('onload', smartRollover);
}