[p-scroller] - Lazy loading + delay lead to infinite loading

MaewenPelletier commented 3 months ago

Describe the bug

Can be reproduce on the demo page of p-scroller https://primeng.org/scroller#lazy-load

Go on the lazy list, scroll down then scroll up to the previous location before the call resolve (the delay parameter 250 in the example)

You are stuck in a infinite loading :

Environment

Bug is present on local (16.9.1) and in the stackblitz provided on the primeng doc aswell ( "primeng": "17.18.9")

Reproducer

https://stackblitz.com/edit/b43ssr-rbmhom?file=package.json

Angular version

17

PrimeNG version

17

Build / Runtime

Angular CLI App

Language

TypeScript

Node version (for AoT issues node --version)

16

Browser(s)

No response

Steps to reproduce the behavior

cf introduction

Expected behavior

It should not display the loader but the data

SPKorhonen commented 2 months ago

I think I've encountered the same problem in 17.18.x

I think I've isolated the problem into onScrollPositionChange.

When it is called for the first time the target.scrollTop gives a reasonable value.
However, if delay is enabled it is called a second time from inside of this.scrollTimeout via this.onScrollChange.
In this invocation target always returns target.scrollTop == 0 which causes all kinds of problems
Unfortunately, I haven't found a definitive reason for the behaviour
If I disable the delay scroller works.
I've also tried caching the result of first invocation and using it in this.onScrollChange which also works

MaewenPelletier commented 1 month ago

@SPKorhonen thansk for the informations !

Maybe completely unrelated but I experienced weird behavior using delay or async with primeng, using ngZone.run(...) solved the problem on other issues.

What your toughs is it something interesting to dig in ?

primefaces / primeng