How to scroll to a selector with a button in the sidebar?

[BurningTreeC]

Hi all,

The sidebar is wrapped into a scrollable widget which intercepts the tm-scroll message

But I'd like to scroll to a domNode which is in the river using a button in the sidebar that dispatches the tm-scroll message with a selector

Is there any possibility doing this or any chance to apply a workaround to the core?

[Jermolene]

Ah, good point. The scrollable widget should not trap tm-scroll messages if they include a selector parameter.

[saqimtiaz]

See #6643 (comment)

[Jermolene]

@Jermolene , @saqimtiaz mentioned that it wouldn't be backwards compatible if we do so
He's in favor of adding a switch like passThrough="yes"

I think all that's needed is for the handler in the scrollable widget to pass the message through if the selector parameter is present.

[saqimtiaz]

I think all that's needed is for the handler in the scrollable widget to pass the message through if the selector parameter is present.

I do not believe that would be backwards compatible @Jermolene.

Consider the following scenario:

• a tm-sroll message with a selector parameter originates from within a scrollable
• the selector targets a DOM element inside the same scrollable
• the tm-scroll message is handled by the scrollable widget and scrolling happens within the scrollable to bring the target element in to view. No scrolling happens at the document level. This is the current behaviour.

If we allow tm-scroll messages with a selector parameter to passthrough the $scrollable widget, the scrolling will be handled at the page/document level and no scrolling will occur inside the scrollable. Unless I am missing something, this will both be inconsistent with current behaviour where no scrolling happens at the document level, and it will also remove the only affordance for programmatically triggering scrolling inside a $scrollable widget from wikitext. This would be a breaking change for several of my wikis.

[Jermolene]

Yes of course, you're quite right. I'd forgotten we'd made the scrollable widget aware of the selector parameter, as well as the page scroller.

Could we pass the tm-scroll through if there is a selector parameter, and also the selector identifies an element that is not a descendent of the scrollable widget?

[saqimtiaz]

Could we pass the tm-scroll through if there is a selector parameter, and also the selector identifies an element that is not a descendent of the scrollable widget?

I'll paraphrase that as allowing the tm-scroll through if there is a selector parameter and no matching element that is a descendant of the scrollable widget, as that seems closer to the current behaviour. Otherwise users would need to ensure that their selectors are unique not only in the scrollable but document wide, breaking current behaviour.

Strictly speaking that would not be backwards compatible either, though not a problem for my particular use case.

Currently you can send a tm-scroll message with a selector inside a scrollable widget in the knowledge that if there is no matching target element in the scrollable, no scrolling will happen. If we then allow that message to propagate, an element outside the scrollable might match and trigger scrolling whereas with the current code that would not happen. My main worry here is that it would remove the affordance of "scroll to this selector if the element exists in the scrollable, otherwise do nothing".