Adding Javascript global Variables to Http Request Session

I have a JSP that includes the following javascript functions to generate a swap list. The Options are 2 collections, hostList and targetHostList which are retrieved from a database on the server and loaded into the request session. The User makes selections and these selecteds are stored in Global Javascript variable selectedOptions. How can I make the javascript variable selectedOptions accessable to the Servlet when it is posted?

Here is the code which I am trying to accomplish this with:
(Java Script Swap List):
// swaplist.js var selectedList; var availableList; function createListObjects(){ availableList = document.getElementById("availableOptions"); selectedList = document.getElementById("selectedOptions"); } function delAttribute(){ var selIndex = selectedList.selectedIndex; if(selIndex < 0) return; availableList.appendChild(selectedList.options.item(selIndex)) selectNone(selectedList,availableList); setSize(availableList,selectedList); } function addAttribute(){ var addIndex = availableList.selectedIndex; if(addIndex < 0) return; selectedList.appendChild(availableList.options.item(addIndex)); selectNone(selectedList,availableList); setSize(selectedList,availableList); } function delAll(){ var len = selectedList.length -1; for(i=len; i>=0; i--){ availableList.appendChild(selectedList.item(i)); } selectNone(selectedList,availableList); setSize(selectedList,availableList); } function addAll(){ var len = availableList.length -1; for(i=len; i>=0; i--){ selectedList.appendChild(availableList.item(i)); } selectNone(selectedList,availableList); setSize(selectedList,availableList); } function selectNone(list1,list2){ list1.selectedIndex = -1; list2.selectedIndex = -1; addIndex = -1; selIndex = -1; } function setSize(list1,list2){ list1.size = getSize(list1); list2.size = getSize(list2); } function getSize(list){ /* Mozilla ignores whitespace, IE doesn't - count the elements in the list */ var len = list.childNodes.length; var nsLen = 0; //nodeType returns 1 for elements for(i=0; i<len; i++){ if(list.childNodes.item(i).nodeType==1) nsLen++; } if(nsLen<2) return 2; else return nsLen; } function showSelected(){ var optionList = document.getElementById("selectedOptions").options; var data = ''; var len = optionList.length; for(i=0; i<len; i++){ if(i>0) data += ','; data += optionList.item(i).value; } alert(data); } function getSelected(){ var optionList = document.getElementById("selectedOptions").options; var data = ''; var len = optionList.length; for(i=0; i<len; i++){ if(i>0) data += ','; data += optionList.item(i).value; } return data }


Your assistance is greatly appreciated

The only way to pass values to Java code would be via a request parameter.

Put a hidden field on the page, and populate it with a comma separated list of selected items.
Your Servlet code can then retrieve that String, parse it and determine the selected options.

That worked for me, thank you.