一个带CheckBox的树形目录的递归算法（javascript）

唉，很久以前写的代码，晒一晒，估计自己看都看不懂了，:(
var head="display:''"
img_close=new Image()
img_close.src="/sysManage/images/f.gif"
img_open=new Image()
img_open.src="/sysManage/images/fo.gif"
img3=new Image()
img3.src="/sysManage/images/e.gif";
var elment = img_close.src
function onMouseDown(){
if(!document.all)return
var eventObj = event.srcElement;
if(eventObj.tagName=="IMG" ) {
//判断是否存在子节点
var sSrc = eventObj.src ;
if(sSrc == null || sSrc.length<=0)return;
if(sSrc.indexOf("e.gif") >= 0)return;
if(sSrc.indexOf("f")<0 && sSrc.indexOf("tree-site")<0 )return;
var nOffIndex = 2;
var srcIndex = eventObj.sourceIndex;
var nested = document.all[srcIndex + nOffIndex];
if(nested.tagName!="DL"){
nested = document.all[srcIndex + 1];
}
if (nested.style.display=="none") {
nested.style.display='inline';
if(sSrc.indexOf("f.gif")>0)
eventObj.src = img_open.src;
}
else {
nested.style.display="none";
if(sSrc.indexOf("fo.gif")>0)
eventObj.src = img_close.src;
}
}else if(eventObj.tagName == "A" ){//相应节点的点击
var nChnlId = parseInt(eventObj.name);
if(!isNaN(nChnlId)){
onClickChannel(nChnlId);
}
}
}
/** 选中某个节点下的所有子节点(主要用于权限树的选择).
* @param obj 节点选择框对象(checkbox对象)
*根据所选节点的值，遍历整个树，从而选中满足条件的节点.
*/
/*
function checkNode(obj) {
for (var i=0;i<form1.chkID.length;i++)
{
if (form1.chkID[i].value.length > obj.value.length &&
form1.chkID[i].value.substring(0,obj.value.length) == obj.value)
{
if(obj.checked)
{
form1.chkID[i].checked = true;
}
else
{
form1.chkID[i].checked = false;
}
}
}
}
*/
function checkNode(obj)
{
var elm = obj.parentNode;
checkChildr