08-06-2015, 12:08 PM
The spoilers are jQuery-based. There's a function that runs on page load that searches for each spoiler on the page and applies some JavaScript to them. If you try to click on a spoiler before the page finishes loading (or, at least, before the JavaScript triggers and enables them), you'll jump to the top of the page since the script that's supposed to fire hasn't been attached yet.