// ZEBRA EFECT
function zebra(idName,tagName,addClassName) {
if (!document.getElementById(idName)) { return false; }

var zebraRows = document.getElementById(idName).getElementsByTagName(tagName);

for (var i=0; i<zebraRows.length; i++) {
if (i%2) {
zebraRows[i].className = addClassName;
}
}
}