Table: Scroller is broken when scrollHeight is flex

[sotjdisc]

Describe the bug

The scrolling experience is broken. Scroll bars are unusable and you cannot scroll to the end of the table with them.

Environment

Chrome: latest

Reproducer

https://stackblitz.com/edit/es8wpw-mesec1

Angular version

17.3.12

PrimeNG version

17.18.9

Build / Runtime

Angular CLI App

Language

TypeScript

Node version (for AoT issues node --version)

whatever stackblitz is using now

Browser(s)

No response

Steps to reproduce the behavior

1. Open stackblitz example and scroll down with mouse wheel
2. Observe scrollbars on the right while scrolling

Expected behavior

1. Same as with primeng version prior to 17.18.8

[SaajRP]

I can confirm that it's completely broken on PrimeNG 17.8.9 and has made virtual scrolling tables, completely unusable. Once, I scroll past the first "page", all entries after it are stuck in a loading state, and the scroll bar jumps around. Changing the virtualScrollItemSize doesn't seem to make a difference, and is only resolved when setting the scrollHeight to a fixed number of pixels

https://stackblitz.com/edit/oetsny-rdsoxe?file=src%2Fapp%2Fdemo%2Ftable-virtual-scroll-lazy-demo.ts

On PrimeNg 17.8.8, it was also broken, with the bugs stated below.

(https://github.com/primefaces/primeng/issues/16185) If I set the virtualScrollItemSize to be less than 50, when I to scrolled to the very bottom of the virtual scrolling, lazy loaded table, I was unable to see the very last few rows in the table, and scrollbar would jump up when trying to scroll to them

(https://github.com/primefaces/primeng/issues/13370) If the table has the rows attribute set, when I scroll from the top to the bottom of the table (so I effectively skipped some "pages" in the middle), then scroll up to the middle of table, the table would be stuck in a loading state - this has been been a bug for over a year, since at least PrimeNG 15.4.1

I believe the virtual scrolling implementation needs to be be re-evaluated as it has a lot of different bugs

[sotjdisc]

It is not related to changes in virtualScrollItemSize . In the example, i am using the default sizes.

[SaajRP]

@sotjdisc, I understand, this bug happens when setting the scrollHeight to 'flex'. I was adjusting the virtualScrollItemSize, to see if there was any relation to the existing bug https://github.com/primefaces/primeng/issues/16185

[ZeroZeroOne-dev]

bump, we're experiencing the same issue

[mkutowski]

Yep most tables using scrollHeight="flex" + virtualScroll="true" are broken. Also the table header disappears halfway when scrolling to 50% of the table.

[Dedme]

i want to blame this commit - https://github.com/primefaces/primeng/commit/e7b611ba4c554aa4beeebe7a8a1ac8d74534507e

i believe this PR will fix it - please merge - as all flexheight tables/trees are broken atm.