var pacity = 100, add = -10, delay = 30, timerID;

function setMessageDivOpacity() {
 opacity += add;
 if (ie4) {
  divMsg.style.filter = "alpha(opacity=" + opacity + ")";
 }
 else {
  divMsg.style.opacity = opacity / 100;
 }

 if (opacity < 0) {
  clearTimeout(timerID);
  divMsg.innerHTML = "";
  divMsg.style.visibility = "hidden";
 }
 else
  timerID = setTimeout("setMessageDivOpacity()", delay);
}

代码在chrome里是正常，不过在ie里却是直接消失，不想引入jquery，不知道有什么更好的办法</DIV>