[Reader] Chapters get skipped when when clicking back/forward a page during the chapter loading transition

[gearsky]

When a user advances to the next page while on the last page of a chapter, there's a period of loading while the reader transitions to the next chapter. If the user then quickly moves to the previous manga page, which would usually return the user to the final page of the preceding chapter, the user is brought to the first page of the chapter before the last one.

Steps to Reproduce:

1. Navigate to a manga and open a chapter that has additional chapters before and after it
2. Navigate to the final page of the chapter
3. Advance the reader to the next page
4. While the next chapter is loading, quickly return the reader to the previous page

Expected Results: The user is returned to the last manga page they were on, namely the final page of the chapter they came from.

Actual Results: The user is directed to the first page of the chapter before the one they came from.

This issue was observed on Firefox ver. 115.0.2 (64-bit) for Windows 10 Home Version 22H2 (OS build: 19045.3208)

Additional Notes:

• From my experience, this does not occur after a certain amount of time has passed during the chapter loading. I believe that there have also been rare occasions where navigating too quickly will also prevent it from occurring, which seems to indicate that there's a specific point during loading where this issue can occur, but I may be misremembering/imagining that.
• This issue has a somewhat inconsistent reproduction rate (hovering somewhere between 3/5 and 4/5, I'd say), though this likely due to the above mentioned specificity of the timing required.
• This issue also occurs in the forward direction, where advancing to the next page too quikcly while loading the previous chapter (after stepping back a page from the first page of a given chapter) will skip the user forwards to the chapter after the one they were coming from. The user is still deposited on the first page of the chapter they're skipped to, instead of landing on the final page of it to perfectly mirror the issue I initially outlined.
• I believe I have also seen this occur in the forward direction while also moving forward (i.e. the case where the user quickly advances the page a second time while loading the next chapter), which also skips the user to the first page of the chapter after the one they were intending to navigate to, but it hasn't happened to me recently enough for me be certain, and I wasn't able to replicate that version during my attempts to reproduce the issue just now. Same thing for going quickly going back a page while loading the previous chapter (which deposits the user on the first page of the chapter before the one they were loading): I believe I've experienced it happen before, but not recently enough to be confident in my memory of it, and I wasn't able to reproduce it in the (admittedly limited) testing of this that I did before I finished submitting this ticket. Still, despite the uncertainty, I figured it was better to mention it than not.

 

[gearsky]

Update: I just had this happen again, and I may have made a mistake in my initial report: It looks like it puts the user on the final page of the chapter before the one they were going to.
It's possible that there are different behaviors that occur, but this time around it definitely put me on the final page of chapter 1 (I was trying to move back to chapter 2 while chapter 3 was still loading).

 

[Atifus]

https://forums.mangadex.org/threads...chapter-does-not-change-url-properly.1328098/

Seems like this one.

 

[gearsky]

https://forums.mangadex.org/threads...chapter-does-not-change-url-properly.1328098/

Seems like this one.

Took a look at the video in that one, and I don't think it's the same issue. That one seems like it's keeping the user on the same chapter. This one involves jumping over entire chapters.

 

[Atifus]

Took a look at the video in that one, and I don't think it's the same issue. That one seems like it's keeping the user on the same chapter. This one involves jumping over entire chapters.

my bad