So just to clarify, this behavior seems to be by design. In that case it does seem the original comment is objectively wrong if the code is readable and maintainable and accomplishes the desired behavior.
As parent comments mention, sending back the whole-page response when you vote on a comment is a great idea if you have JavaScript disabled or aren't logged in.
But it'd be a quick performance win if it didn't do that when you were logged in with JavaScript enabled. The actual JavaScript part of this is actually already implemented -- that's why the page doesn't refresh when you upvote my comment -- so you'd just need one if-statement on the server side to send a blank response instead of a redirect.
Sure, 10 KB of download and the server CPU time needed to re-generate the listing page is probably pretty negligible, but multiply that by the number of votes casted on Hacker News every day and it starts to add up.
Exactly, and it even adds up quickly for a single user in common cases like voting on a bunch of comments while reading a thread.
If someone loads this thread right now, the initial page load is 61KB (gzipped). If they read down the thread and vote on 30 comments while they're doing it, they transfer an additional 480KB (16KB/vote [1]). There's no reason that they should be receiving 8x more data by voting on a relatively low number of comments (~10% of the thread) than they did when loading the entire page originally. It also has to re-generate the page an extra 30 times unnecessarily - a repeatedly voting user becomes like a heavy multiplier to your traffic.
[1]: Also, I just noticed that the responses back from voting actually aren't the full page, they're truncated. It seems like maybe the response size is capped at 16KB gzipped? That implies that there's already some kind of special handling for the voting responses.
From what i can see, the response only contains the comment you upvoted and its children. It's important for people like me who don't have Javascript, but the JS voting system could probably do with a simple HEAD request.
Seconding. Sending back the whole page on AJAX upvote seems unnecessarily wasteful, and sounds like something trivially fixable.
Taking data from 2.5 years ago[0], HN has ~300k daily uniques. Assuming 10% of that are users, each upvoting one story, that's 30k unnecessary page renders per day. That's ~2% of the total views (though the more expensive views - AFAIK when you're logged out, you get cached pages?), so on the one hand it's not much, but on the other hand the fix should be trivial and have minimal impact on code readability.
But it'd be a quick performance win if it didn't do that when you were logged in with JavaScript enabled. The actual JavaScript part of this is actually already implemented -- that's why the page doesn't refresh when you upvote my comment -- so you'd just need one if-statement on the server side to send a blank response instead of a redirect.
Sure, 10 KB of download and the server CPU time needed to re-generate the listing page is probably pretty negligible, but multiply that by the number of votes casted on Hacker News every day and it starts to add up.