Only render updated items in an array about zustand HOT 4 CLOSED

Perfect, that does the trick! Thankyou!

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I think it might be because you don't have a key on each element. React uses keys to know which item has changed or has been removed/added to the list. Without a stable identity, it doesn't know and renders everything again.

<div className="App">
  {divs.map((d, i) => (
-    <DivEl color={d} index={i} />
+    <DivEl color={d} index={i} key={i} />
  ))}
</div>

Now using indexes as keys is not always good, it depends if the items in the list will have their order changed eventually. In that case you might need something that is uniquely tied up to each item.

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Sorry, that was clumsy of me, but the keys don't make a difference. I've updated the codesandbox above and all items still rerender when only one item has changed.

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Sorry I got confused as well :). Not having stable keys would actually force React to destroy and create items on each render pass because it doesn't know which items got updated/added/removed since the keys are different (or no keys at all).

The fact that all DivEl re-renders is normal because its parent re-renders due to the Divs state slice to update in the store. To avoid unnecessary renders, we can leverage memo which would do a shallow equal comparison on the props and abort rendering if they haven't changed.

I forked your sandbox and used memo: https://codesandbox.io/s/musing-curran-gwnor

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