How can I grab a div from an iframe into a JS variable? You don't have to use jQuery.
document.getElementById('IframeId').contentWindow.document.getElementById('DivId');
In jQuery syntax it would be $('iframe').contents().find('div') . (Please replace any specific identifiers / classes / other selectors you need). Tracker1's answer should work fine for standard Javascript.
$('iframe').contents().find('div')