js脚本在火狐浏览器中不兼容怎么办啊

js脚本在火狐浏览器中不兼容怎么办啊   对JS不是很了解  请高手帮忙修改  这个在IE中是好用的
代码如下
<script LANGUAGE="JavaScript">
  document.onmouseover = doDocumentOnMouseOver ;
  document.onmouseout = doDocumentOnMouseOut ;  function doDocumentOnMouseOver() {
    var eSrc = window.event.srcElement ;
    if (eSrc.className == "item") {
      window.event.srcElement.className = "highlight";
    }
  }  function doDocumentOnMouseOut() {
    var eSrc = window.event.srcElement ;
    if (eSrc.className == "highlight") {
      window.event.srcElement.className = "item";
    }
  }
var bV=parseInt(navigator.appVersion);
NS4=(document.layers) ? true : false;
IE4=((document.all)&&(bV>=4))?true:false;
ver4 = (NS4 || IE4) ? true : false;function expandIt(){return}
function expandAll(){return}
</script><script LANGUAGE="JavaScript1.2">
<!--
isExpanded = false;function getIndex(el) {
        ind = null;
        for (i=0; i<document.layers.length; i++) {
                whichEl = document.layers[i];
                if (whichEl.id == el) {
                        ind = i;
                        break;
                }
        }
        return ind;
}function arrange() {
        nextY = document.layers[firstInd].pageY + document.layers[firstInd].document.height;
        for (i=firstInd+1; i<document.layers.length; i++) {
                whichEl = document.layers[i];
                if (whichEl.visibility != "hide") {
                        whichEl.pageY = nextY;
                        nextY += whichEl.document.height;
                }
        }
}function initIt(){
        if (NS4) {
                for (i=0; i<document.layers.length; i++) {
                        whichEl = document.layers[i];
                        if (whichEl.id.indexOf("Child") != -1) whichEl.visibility = "hide";
                }
                arrange();
        }
        else {
                tempColl = document.all.tags("DIV");
                for (i=0; i<tempColl.length; i++) {
                        if (tempColl(i).className == "child") tempColl(i).style.display = "none";
                }
        }
}function expandIt(el) {
        if (!ver4) return;
        if (IE4) {expandIE(el)} else {expandNS(el)}
}function expandIE(el) {
        whichEl = eval(el + "Child");
        whichIm = eval(el+"Img");        if (whichEl.style.display == "none") {
                whichEl.style.display = "block";
                whichIm.src = "Images/Icon-.gif";
        }
        else {
                whichEl.style.display = "none";
                whichIm.src = "Images/Icon+.gif";
        }
    window.event.cancelBubble = true ;
}function expandNS(el) {
        whichEl = eval("document." + el + "Child");
        whichIm = eval("document." + el + "Parent.document.images['imEx']");
        if (whichEl.visibility == "hide") {
                whichEl.visibility = "show";
                whichIm.src = "Images/Icon-.gif";
        }
        else {
                whichEl.visibility = "hide";
                whichIm.src = "Images/Icon+.gif";
        }
        arrange();
}function showAll() {
        for (i=firstInd; i<document.layers.length; i++) {
                whichEl = document.layers[i];
                whichEl.visibility = "show";
        }
}function expandAll(isBot) {
        newSrc = (isExpanded) ? "Images/Icon+.gif" : "Images/Icon-.gif";        if (NS4) {
                for (i=firstInd; i<document.layers.length; i++) {
                        whichEl = document.layers[i];
                        if (whichEl.id.indexOf("Parent") != -1) {
                                whichEl.document.images["imEx"].src = newSrc;
                        }
                        if (whichEl.id.indexOf("Child") != -1) {
                                whichEl.visibility = (isExpanded) ? "hide" : "show";
                        }
                }                arrange();
                if (isBot && isExpanded) scrollTo(0,document.layers[firstInd].pageY);
        }
        else {
                divColl = document.all.tags("DIV");
                for (i=0; i<divColl.length; i++) {
                        if (divColl(i).className == "child") {
                                divColl(i).style.display = (isExpanded) ? "none" : "block";
                        }
                }
                imColl = document.images.item("imEx");
                for (i=0; i<imColl.length; i++) {
                        imColl(i).src = newSrc;
                }
        }        isExpanded = !isExpanded;
}
//定义字体颜色
with (document) {
        write("<STYLE TYPE='text/css'>");
        if (NS4)
        {
        write(".parent {font-family: Verdana, Arial, Helvetica, sans-serif; color: #000000; text-decoration:none; position:absolute; visibility:hidden; color: black;}");
        write(".child {font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 8pt;color: #000000; position:absolute; visibility:hidden}");
        write(".item { color: blue; text-decoration:none;}");
        write(".regular {font-family: Arial,Helvetica,sans-serif; position:absolute; visibility:hidden}");
        write("DIV { color:black; }")
        }
        else
        {
        write(".child {font-family: Verdana, Arial, Helvetica, sans-serif; color: #000000; text-decoration:none; display:none}");
        write(".parent {font-family: Verdana, Arial, Helvetica, sans-serif; color: #000000; text-decoration:none;}");
        write(".item { color:blue; text-decoration:none; font-size: 9pt;}");
        write(".items { color:blue; text-decoration:none; font-size: 9pt;}");
        write(".highlight { color: #0166b4; font-size: 9pt;}");
        write(".heada { color: black;font: 12px; Times}");
        write("DIV { color:black; }")
            }
        write("</STYLE>");}onload = initIt;
//-->
</script>