function rollon() {
  if (event.srcElement.tagName != "A") return
  else
  {
    event.srcElement.style.color = "red";
  }
}

function rolloff() {
  if (event.srcElement.tagName =="A")
 {
    event.srcElement.style.color = "";
 }
}
document.onmouseover = rollon;
document.onmouseout = rolloff;