feat: add API to pause scroll position saving

[hedgepigdaniel]

In Rudy it is possible that updateScroll is not called immediately after a transition (rather it might occur asynchronously afterwards).

Further, the content of the new route might not be rendered immediately. for example, the following things might happen

1. transitionHook called to indicate that a transition is about to occur
2. URL changes
3. loading spinner is displayed as the page content
4. asynchronous API request is done
5. final page content is rendered
6. updateScroll is called to restore the scroll position on the new route

Sometimes, scroll events happen at steps 3 or 5, because the page content height reduces such that it is lower than the current window.scrollY value. In this case, it is not desired to save the scroll position, because it is just noise occurring during the transition.

This adds a flag _isTransitioning which is used to skip saving the scroll position in between calls to the transition hook and updateScroll. The assumption is that updateScroll is always called after every transition.

[taion]

I'm really sorry for the delay here. We've been swamped at work lately. I'll take a look by early next week. Unfortunately probably not this weekend

[hedgepigdaniel]

No problem, thanks for you help so far - I'll be grateful if you can have a look soon.

I'd like to make the tests cover his change but it looks like that would require a bit of surgery on he test setup - to make it call updateScroll not immediately after the URL transition.

[taion]

can you merge with master to avoid the conflicts with your other PR?

[hedgepigdaniel]

conflict fixed

[hedgepigdaniel]

any chance of getting to this soon?

[taion]

sorry, i've been really swamped. i'll look by end of week

[taion]

apologies for the delay here

[hedgepigdaniel]

Besides implementing your suggestion for the API, I also added tests (which was easier with this API), and in the process fixed a bug that prevented this feature from working for custom elements.

I think it's ready now.

[taion]

published to v0.9.11

[taion]

thanks for your help here – sorry for the delay

[hedgepigdaniel]

No worries, thankyou!