[BUG] update scroll position should only be called once #242
+82
−6
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routeDidChange
is called more than once indeterminately.scheduleOnce
will run once IFF the same callback ref is given to it. This PR fixes that and is the easy part of this PR.The difficult part of this PR -
whenRouteIdle
needs to be resolved and scroll position updated when we are done callingrouteDidChange
. Effectively the last call is the last argument. We don't want to update the scroll position somewhere in the middle. So the difficult part of this is when to resolve. We do this withrequestAnimationFrame
and a counter.In algorithmic terms, this is a stack (and more like a deferred stack because the producer of the items does not know when it done pushing new items onto the stack. It only attempts to pop the last item from the stack when it is done pushing new items on the stack and an arbitrary count gets back to 0).