从Sharepoint列表Web服务返回并保存XML对象

I am trying to populate a variable with an XML response from an ajax call on page load so that on keyup I can filter through that list without making repeated get requests (think very rudimentary autocomplete). The trouble that I am having seems to be potentially related to variable scoping but I am fairly new to js/jQuery so I am not quite certain.I am trying to populate a variable with an XML