Please don't do that. I left that tab open on purpose, I'm half way through reading the page - if the page refreshes I likely lose my position
quick pjax e.g.:
<html data-lastupdated="1234567890"...
$.getJSON('/lastupdated.json', function(lastupdated) {
if(lastupdated > $('html').data('lastupdated'))
{
$('a[data-pjax]').removeAttr('data-pjax');
}
});