onRest is called again after rerender

[ThomasDeutsch]

Problem: Once completed, onRest function is called on every rerender.

minimal codesandbox demo

Expected: the count should only increment once.
Current Behaviour: after rerender the onRest function is called again, and the count gets updated.

Versions in this demo:
"react-spring": "8.0.19",
"react": "16.8.3",
"react-dom": "16.8.3"

[drcmda]

It's how onRest is currently working, it animates between 100% and 100% and comes to a rest immediately. If if didn't do that, then you couldn't await async animations, since onRest wouldn't be called once you animate towards a value that's already set.

[ThomasDeutsch]

understood, thanks for the explanation.

But how can i change the state once, after the animation has finished?
It would be possible if i could get the from-values in onRest like:

onRest(to, from) {
  if(to.width !== from.width) {
   setState(i+1);
  }
} 

[aleclarson]

This will be fixed by #615

[aleclarson]

You can use v9 like this now: yarn add react-spring@next

Let us know how it goes: #642