请帮忙解读一段代码..
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN ">
<html>
<head>
<style type= "text/css ">
.wc, #wc1, #wc2 {
position:absolute;
border-width:0px;
z-index:2;
left:0px;
top:0px;
display:none;
}
#wc1 {
width:320px;
height:240px;
background-color:#FFCC00;
}
#wc2 {
width:420px;
height:340px;
background-color:#CCCCCC;
}
.wc {
z-index:1;
}
</style>
<script type= "text/javascript ">
(function () {
var interval = window.setInterval;
window.setInterval = function (a, b) {
var fun;
if ( "function " == typeof a) {
var arg = Array.prototype.slice.call(arguments, 2);
fun = function () {
a.apply(null, arg);
};
} else {
fun = a;
}
return interval(fun, b);
};
})();
function createOpenMenu(changeTime) {
var intervalTime = 5, wc_number = 0;
function addIframe() {
//添加一个Iframe为了遮盖住IE的Select...
var ifr = document.createElement( "iframe ");
ifr.setAttribute( "id ", "ifr_ " + (++ wc_number));
ifr.setAttribute( "className ", "wc ");
ifr.setAttribute( "class ", "wc ");
document.body.appendChild(ifr);
return $( "ifr_ " + wc_number); //返回新加入的Iframe...
}
function changeMenu(o) {
//改变对象属性..以达到收缩效果...
if (eval(o.bool)) {
o.t_iframe.style.width = o.style.width = (o.t_num * o.t_width) + "px "; //设置Iframe和div的宽度..
o.t_iframe.style.height = o.style.height = (o.t_num * o.t_height) + "px "; //设置Ifrmae和div的高度..
o.t_iframe.style.left = o.style.left = o.t_left - o.offsetWidth / 2 + "px "; //设置Iframe和div的Left位置...
} else {
if (/ </.test(o.bool)) { //如果是over的时候结束了的话,那么就显示内容..
o.innerHTML = o.context;
} else { //否则就把Iframe和div隐藏...
o.t_iframe.style.display = o.style.display = "none ";
}
window.clearInterval(o.timer); //清楚记时器
}
}
function over() {
//当鼠标经过时..执行...
var o = this.o;
var par = this.p;
o.bool = "++ o.t_num < changeTime "; //改变判断..
if (o.t_num <= 0 || "undefined " == typeof o.timer) { //如果记时器为空的时候
o.innerHTML = " "; //内容设置为空
o.t_iframe.style.display = o.style.display = "block "; //设置为显示
o.t_iframe.style.width = o.style.width = "0px ";
o.t_iframe.style.height = o.style.height = "0px ";
o.t_iframe.style.left