p-table virtual scroll event is triggering even on scroll up

[pachu4u]

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Current behavior

The virtual scroll event gets triggered even when scrolled up with lazy loading. The same can be seen in official demo of the scroll functionality.
Expected behavior

Event should be triggered only while scrolling down
Minimal reproduction of the problem with instructions
Scroll up and down on the official demo

What is the motivation / use case for changing the behavior?

Please tell us about your environment:

• Angular version: 5.X

angular 8.2.3

• PrimeNG version: 5.X

latest 9.0.6

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• Node (for AoT issues): node --version =

[pachu4u]

I also tried a work around like this. Unfortunately with this the loading-body /loading text doesn't disappear. Does it expect the total records to be increased every time the function is called?

loadDataOnScroll(event: LazyLoadEvent) { console.log(event); if(this.scrollOffset < event.first) { this.scrollOffset = event.first; this.getNextPage(); } }

I see no use of setting this.loading to true or false.

[cagataycivici]

VirtualScrolling for Table is reimplemented from the ground up (#8855) and this particular case i no longer an issue with the new implementation. Thank you for the feedback.

[brayanL]

Hello guys, this is still present in the latest version, even in your demo:
https://www.primefaces.org/primeng/table/virtualscroll
How can I remove the scroll-up with lazy loading? Thanks.

[mertsincan]

Hi, you can use appendOnly:true option in virtualScrollerOptions property or you need to write a cache algorithm yourself in lazy method.
https://www.primefaces.org/primeng/scroller

[brayanL]

@mertsincan thanks for your reply but that property is not present in virtualScrollerOptions:

export interface ScrollerOptions { id?: string | undefined; style?: any; styleClass?: string | undefined; tabindex?: number | undefined; items?: any[]; itemSize?: any; scrollHeight?: string | undefined; scrollWidth?: string | undefined; orientation?: ScrollerOrientationType; delay?: number | undefined; lazy?: boolean; disabled?: boolean; loaderDisabled?: boolean; columns?: any[] | undefined; showSpacer?: boolean; showLoader?: boolean; numToleratedItems?: any; loading?: boolean; autoSize?: boolean; trackBy?: any; onLazyLoad?: Function | undefined; onScroll?: Function | undefined; onScrollIndexChange?: Function | undefined; }

[brayanL]

The last version of primeng has that property appendOnly I was using version 14. Please update the tables on your website or provide better documentation. Thanks for your awesome work.