Scroll position is not persisted with RouteReuseStrategy

[ymita]

Description

IgxGrid does not persist its scroll position when the grid is reused by RouteReuseStrategy.

• igniteui-angular version: 10.1.3
• browser: n/a

Steps to reproduce

1. Run the sample
2. Scroll vertically and horizontally
3. Click the button at the bottom to move to other page
4. Click the button to go back to the original page

Result

Both vertical and horizontal scrollbars are reset to the initial positions.

Expected result

Both vertical and horizontal scrollbars should remain the positions where these are scrolled.

Attachments

igx-grid-scroll-position.zip

[ChronosSF]

@ymita ,

Discussed this with @rkaraivanov , and as RouteReuseStrategy is currently implemented, fixing this would require introducing yet another mutation observer of some sort. This is because angular doesn't provide hooks that would allow us to update stuff that are broken between detaches (such as the scroll position).

There is an angular issue: angular/angular#27290 that suggests adding such hooks so I would like to postpone fixing this to when angular decide to improve their RouteReuseStrategy.

[ChronosSF]

As discussed in #8272, we'll add a mutation observer to resolve this. @ymita , do we need to target old versions with this fix or we can implement it for 10.2 and later only?

[ymita]

@norikois For the fix of this issue, are we fine with 10.2 and later?

[norikois]

@ymita
Thank you for pinging me.

@ChronosSF
Could you fix this for 10.1 as well as 10.2, which are the versions in maintenance period?

[ChronosSF]

We only plan one more release for 10.1 , @kdinev , @radomirchev , should we postpone it a little bit so that this fix can get in?

[kdinev]

@ChronosSF We will release 10.1 until all the pending PRs to it are merged. No need to postpone a current tag, we will just continue tagging until there's deltas from the previous tag.

[ChronosSF]

I've been testing the mutation observer for a while and it seems to work, however:

• The issue in Which properties or features IgxGrid will not persist over RouteReuseStrategy? #8272 is unrelated and won't be fixed with this one. The columns get pixel widths after reattaching to the DOM because a separate observer detects this as a "resize" and switches them to pixels as we don't support resizing columns in % widths.

• To make the new observer work on IE11 @MayaKirova had to add some debounce time which makes the scroll restoration noticeable (as it happens a certain amount of ms after the DOM reappears).

If @rkaraivanov , @kdinev , @radomirchev , @ymita are fine with this caveats we can proceed with merging the PR .