Preact: Strange key comparison during reconciliation

Created on 7 Aug 2017 · 6Comments · Source: preactjs/preact

preact.esm.js, line 703
if (inst && inst.constructor === childComponent && childProps.key == inst.__key) {

My application have an issue - unnecessary react-redux connected component unmount at app startup. I sure that the component keys remain same and component/element stays same. During debugging, i see that at line 703 childProps.key whas always undefined, despite of I declared it in component props.

I try to build a simplifier test case, but wanna ask - is this line of code covered by tests?

pending

Source

koutsenko

Most helpful comment

There will be an announcement regarding keys shortly :)

developit on 24 Jan 2018

👍2

All 6 comments

Hmm - are you diffing against an SSR-generated DOM?

developit on 7 Aug 2017

Nope. Just using preact, redux and react-redux connector.
The issue occurs on "connected" components after redux state updates.
And I get a remounts instead of updates. How can i fiddle test case (which service to use)?

koutsenko on 7 Aug 2017

👍2

Just to add more info here. On removing the key on the component in a list, it starts updating the component on redux state update like it should instead of mount and unmount when key was present.

okmanideep on 10 Aug 2017

👍2

any progress?

goodmind on 24 Sep 2017

There will be an announcement regarding keys shortly :)

developit on 24 Jan 2018

👍2

A lot of fixes with keys have landed in master in the past few days. The last known issues will be resolved with #1440 . In my testing I was not able to find any further issues with keys. Feel free to ping us if the issue isn't resolved with our next release (beta or alpha.5) :+1: