Hook that emits the previous and current values of useState()

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Hook that emits the previous and current values of useState()

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Last edited Jun 29, 2021

Created on Dec 30, 2021

This example demonstrates a React hook that tracks both the previous and current values of a state variable, returning them as a pair for comparison or animation. The `useStatePair` hook initializes with an undefined previous value and the provided initial state, then uses a `setPair` callback to update the tuple whenever `setValue` is called. It relies on React’s `useState` and `useCallback` APIs to manage the state pair and memoize the update function, ensuring stable references. The code shows a generic pattern for observing state transitions without additional libraries.

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