"all without incurring the cost of a full page load." Except that it just downloaded the whole page. Forget about any javascript that runs on doc ready in that

"all without incurring the cost of a full page load." Except that it just downloaded the whole page. Forget about any javascript that runs on doc ready in that fetched page, it wont run. It also caches a bunch of pages in memory, leaks event listeners etc! Let the fun begin!