封装几个有用的函数

//设置透明度
function setOpacity(node,level){
node=typeof node=="string"?document.getElementById(node):node;
if(document.all){
node.style.filter='alpha(opacity='+level+')';
}else{
node.style.opacity=level/100;
}
}
//阻止冒泡
function stopPropagation(e){
e=window.event||e;
if(document.all){
e.cancelBubble=true;
}else{
e.stopPropagation();
}
}
//使用attachEvent和addEventListener代替on xxx
function on(node,eventType,handler){
node=typeof node=="string"?document.getElementById(node):node;
if(document.all){
node.attachEvent("on"+eventType,handler);
}else{
node.addEventListener(eventType,handler,false);
}
}