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Discussion on: React: Using State in Functional Components

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tiagojpdias profile image
Tiago Dias •

Be careful about that code snippet regarding useState update function.

// index is 10
...
setIndex(index + 1) // next iteration index = 11
(...)
setIndex(index + 1) // next iteration index = 11
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But if you read the documentation about functional updates then you'll have to use a callback to grab the latest value.

This is important whenever you're updating a state using the previous state for calculations.

// index is 10
...
setIndex((index) => index + 1) // next iteration index = 11
(...)
setIndex((index) => index + 1) // next iteration index = 12
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austinbrownopspark profile image
Austin Brown • • Edited

Thanks! I actually have seen it both ways and was confused about why they both work so that is really helpful