rerender-functional-setstate

SKILL.md

When updating state based on the current state value, use the functional update form of setState instead of directly referencing the state variable. This prevents stale closures, eliminates unnecessary dependencies, and creates stable callback references.

The first callback is recreated every time items changes, which can cause child components to re-render unnecessarily. The second callback has a stale closure bug—it will always reference the initial items value.

Note: If your project has React Compiler enabled, the compiler can automatically optimize some cases, but functional updates are still recommended for correctness and to prevent stale closure bugs.

Use functional setState updates to prevent stale closures and unnecessary callback recreations. Apply when updating state based on the current state value in React components. Source: theorcdev/8bitcn-ui.

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