It's possible to test for the existence of an HTML element using jQuery. For one example:
It is possible to do the same for an element that is inside an iframe? My best attempt:
if($("#frameId").contents().find('elementName').length > 0)
{
// do something with the element
}
EDIT: To avoid chasing the cross-domain rabbit, assume that yes, the files are (will be) in the same domain.