学习在线答疑系统遇到的问题
var zdcount=0;//遮挡物隐藏计数器
function getElementPos(elementId)
{
var ua = navigator.userAgent.toLowerCase();
var isOpera = (ua.indexOf('opera') != -1);
var isIE = (ua.indexOf('msie') != -1 && !isOpera);
// not opera spoof
var el = document.getElementById(elementId);
if(el.parentNode == null || el.style.display == 'none')
{
return false;
}
var parent = null;
var pos = [];
var box;
if(el.getBoundingClientRect)
{ //IE
box = el.getBoundingClientRect();
var scrollTop = Math.max(document.documentElement.scrollTop, document.body.scrollTop);
var scrollLeft = Math.max(document.documentElement.scrollLeft, document.body.scrollLeft);
return {x:box.left+ scrollLeft, y:box.top + scrollTop,w:box.right-box.left,h:box.bottom-box.top};

}
else if(document.getBoxObjectFor)
{ // FireFox
box = document.getBoxObjectFor(el);
var borderLeft = (el.style.borderLeftWidth)?parseInt(el.style.borderLeftWidth):0;
var borderTop = (el.style.borderTopWidth)?parseInt(el.style.borderTopWidth):0;
pos = [box.x - borderLeft, box.y - borderTop,box.width,box.height];
}
else
{
// safari & opera
pos = [el.offsetLeft,el.offsetTop,el.offsetWidth,el.offsetHeight];
parent = el.offsetParent;
if (parent != el)
{
while (parent)
{
pos[0] += parent.offsetLeft;
pos[1] += parent.offsetTop;
parent = parent.offsetParent;
}

}
if (ua.indexOf('opera')!=-1||( ua.indexOf('safari')!=-1 && el.style.position == 'absolute' ))
{
pos[0] -= document.body.offsetLeft;
pos[1] -= document.body.offsetTop;
}
return {x:pos[0]+2,y:pos[1]+2,w:pos[2],h:pos[3]};
}
if (el.parentNode)
{
parent = el.parentNode;
}
else { parent = null; }
while (parent && parent.tagName != 'BODY' && parent.tagName != 'HTML')
{ // account for any scrolled ancestors
pos[0] -= parent.scrollLeft;
pos[1] -= parent.scrollTop;
if (parent.parentNode)
{
parent = parent.parentNode;
}
else
{
parent = null;
}
}
return {x:pos[0],y:pos[1],w:pos[2],h:pos[3]};
}

//显示错误信息气球的方法
function showMsg(msg,id)//msg为错误消息文本===id为错误输入控件id
{
//获取错误输入控件的位置、尺寸
tfpos=getElementPos(id);
xby=tfpos.y+tfpos.h-1;
xbx=tfpos.x+tfpos.w/2;

//显示错误信息表格
document.all.myerr.style.left=xbx-70;
document.all.myerr.style.top=xby+18;
document.all.myerrs.innerHTML=msg;
document.all.myerr.style.visibility="visible";

//显示表格上的尖角图片
document.all.myup.style.left=xbx-40;
document.all.myup.style.top=xby-2;
document.all.myup.style.visibility="visible";

//获取错误信息表格位置、尺寸
bgpos=getElementPos("myerr");

//显示遮挡span
document.all.errzd.style.left=xbx-70;
document.all.errzd.style.top=xby+18;
document.all.errzd.style.width=bgpos.w;
document.all.errzd.style.height=bgpos.h;
document.all.errzd.style.visibility="visible";

//启动遮挡隐藏
zdcount=5;
span=bgpos.h/zdcount;
setTimeout("xyzd("+span+","+(xby+18)+")",0);
}

//逐渐隐藏遮挡物
function xyzd(span,top)
{
if(zdcount==0)
{
document.all.errzd.style.visibility="hidden";

}
else
{
document.all.errzd.style.height=span*zdcount;
document.all.errzd.style.top=top+span*(5-zdcount);
zdcount--;
setTimeout("xyzd("+span+","+top+")",50);
}
}

这个脚本程序看不懂，拜托各位讲解，每人讲一点
function hideErr()
{
document.all.myerr.style.visibility="hidden";
document.all.myup.style.visibility="hidden";
document.all.errzd.style.visibility="hidden";
}
function showMenu(id){
var recTemp=getElementPos("my");
var aa = document.getElementById(id);
aa.style.top=recTemp.y+recTemp.h-4;
aa.style.left=recTemp.x+recTemp.w/2-110;
aa.style.visibility="visible";
}
function hideMenu(id){
var aa = document.getElementById(id);
aa.style.visibility="hidden";
}
[最优解释]
显然是隐藏dom对象和显示dom对象啊
[其他解释]
多谢，意识到要去学习DOM了