function replaceA() {
    var list = document.getElementsByTagName("span");
    if (list != null) {
        var i;
        for (i=0; i<list.length; i++) {
            var element = list[i];
            if (element.getAttribute('name') == 'a') {
                var value = element.firstChild.nodeValue.replace(/\(a\)/,"@");
                element.replaceChild(document.createTextNode(value), element.firstChild);
            }
        }
    }
}