Timestamp weirdness: multiplying minutes by 100 then truncating causes strange behaviour

[kaberett]

Dre has diagnosed the problem (see comments). Apparent lack of in-code comments, however, means it is not immediately apparent why we're doing this or what will break if we stop. Nonetheless it should probably be fixed.

---

We've had several reports now of weird stuff going on with timestamps for people using the "Use time entry is posted" checkbox on the Create Entries beta since the sticky-ticky was introduced.

Support request: " Sometimes (possibly related to the above, as it happens every time I compose two posts one after the other) a post will get a future time stamp. I think, but I'm not sure, that it gets marked into the future by the same interval as it took me to compose the post. (i.e. if I started composing a post at 12:00 and posted at 12:45, the post will get tagged with 13:30.)" (http://www.dreamwidth.org/support/see_request?id=31153)

Conversation in IRC:
07:05 < AlexSeanchai> see http://alexseanchai.dreamwidth.org/946340.html which says posted at 01:50 am? I posted it at 01:05.
07:06 < AlexSeanchai> right before I clicked post, the timestamp box of course had the time at which I opened the post window. which was actually 01:02, but the box said 01:20.
07:06 < AlexSeanchai> single-digit minute numbers are showing in the tens column instead of the ones column.
07:06 < AlexSeanchai> how to fix is beyond me.
07:09 < AlexSeanchai> ...that is to say, I figured out a problem with my freaking timestamps. I was gonna post another post to test, editing after 1:10 hits, but the timestamp box on the update page says 02:30. dunno where that came from.

I've also observed some weirdnesses but haven't had the cope/brain to work out what on earth is going on. Filing per @rahaeli's comment over in dw-dev in the interests of diagnosing what the problem is.

[kaberett]

18:10 < AlexSeanchai> wait hold up a minute. the bug where a timestamp of 12:03 shows up as a timestamp of 12:30? if the timestamp is actually 12:09, and therefore shows as 12:90, would that actually show as 01:30? because uh. that makes sense as a thing that happened to http://alexseanchai.dreamwidth.org/950691.html

NB I think this is happening for two (or more) posts made "close together" (for some value of "close together", not sure what) when the use-time-of-posting box is checked by default

[anall]

This in fact has nothing to do with the "sticky-ticky", except it is triggering the bug.

The code for "Use current time" inexplicably multiplies the minutes by 100 before zero-padding the number to two digits.

I am assuming some later code grabs the first 2 digits for the hour, some seperator, and then the next two digits for the minute.

11:09 ends up as 11:900. Which then ends up as 11:90 ( or 12:30 )
11:10 ends up as 11:1000. Which then ends up as 11:10

Observe:
http://exor676.dreamwidth.org/84891.html
http://exor676.dreamwidth.org/85302.html

( To reproduce, I turned on the "Display Date" panel, removed maxsize from the time field using Inspect Element in chrome, and manually modifying that field )

[rahaeli]

That .... is really really weird. Where is it doing that and when was it started?

[kareila]

The change appears to date from last fall, when the beta update page was converted to Foundation.

I found it in htdocs/js/pages/entry/new.js (which is only used on the beta update page).

In function setTimeToNow() around line 680 is the following line:

var time = [ zeropad(now.getHours()), zeropad(now.getMinutes() * 100) ];

I'm completely confused, because the zeropad function prepends a zero to any number less than ten, but multiplying the number of minutes by 100 ensures it will never be less than ten... I think just removing the * 100 would fix the bug?

[rahaeli]

Paging @afuna to see if she remembers why that was done that way!

[afuna]

No clue sadly! Probably just a bug that crept in.

[rahaeli]

Okay! I figured I'd check first to see if it had been deliberate for some reason :)