Need help summoning specific content into container div on page load

[simcoweb]

I'm using this Ajax script to summon content into a container div within the same page as the hyperlinks/menu. What I need is to figure out how I can externally hyperlink to the page and have a specific content displayed in the container div upon page load.

 

So, basically I have 6 links in page A that summon content via external .html files into a container div called 'mainright'. What I want to do is place a hyperlink in Page B or C that summons Page A but displays say the 3rd item from Page A's menu in the 'mainright' div on load.

 

Here's my script:

 

<script type="text/javascript">

var bustcachevar=1 //bust potential caching of external pages after initial request? (1=yes, 0=no)
var loadedobjects=""
var rootdomain="http://"+window.location.hostname
var bustcacheparameter=""

function ajaxpage(url, containerid){
var page_request = false
if (window.XMLHttpRequest) // if Mozilla, Safari etc
page_request = new XMLHttpRequest()
else if (window.ActiveXObject){ // if IE
try {
page_request = new ActiveXObject("Msxml2.XMLHTTP")
} 
catch (e){
try{
page_request = new ActiveXObject("Microsoft.XMLHTTP")
}
catch (e){}
}
}
else
return false
page_request.onreadystatechange=function(){
loadpage(page_request, containerid)
}
if (bustcachevar) //if bust caching of external page
bustcacheparameter=(url.indexOf("?")!=-1)? "&"+new Date().getTime() : "?"+new Date().getTime()
page_request.open('GET', url+bustcacheparameter, true)
page_request.send(null)
}

function loadpage(page_request, containerid){
if (page_request.readyState == 4 && (page_request.status==200 || window.location.href.indexOf("http")==-1))
document.getElementById(containerid).innerHTML=page_request.responseText
}

function loadobjs(){
if (!document.getElementById)
return
for (i=0; i<arguments.length; i++){
var file=arguments[i]
var fileref=""
if (loadedobjects.indexOf(file)==-1){ //Check to see if this object has not already been added to page before proceeding
if (file.indexOf(".js")!=-1){ //If object is a js file
fileref=document.createElement('script')
fileref.setAttribute("type","text/javascript");
fileref.setAttribute("src", file);
}
else if (file.indexOf(".css")!=-1){ //If object is a css file
fileref=document.createElement("link")
fileref.setAttribute("rel", "stylesheet");
fileref.setAttribute("type", "text/css");
fileref.setAttribute("href", file);
}
}
if (fileref!=""){
document.getElementsByTagName("head").item(0).appendChild(fileref)
loadedobjects+=file+" " //Remember this object as being already added to page
}
}
}

</script>

 

I'm not well versed on Ajax/Javascript. Yet   So looking for some help in how this can be done. I'm assuming a function would be created to allow for something like:

 

www.sitename.com/pageA.html?mainright=3

 

or something like that, where the ?mainright=3 (or possibly it should be a reference to the menu class name) would summon the right content into the container div.

 

Thanks in advance!