What does `useCallback` do and when should you use it?

Summary

useCallback caches a function identity between renders while its dependencies stay the same.

Longer Answer

It is mostly useful when passing callbacks to memoized children, using a callback in another hook dependency list, or avoiding resubscription to imperative APIs. It does not make the function itself faster; it only stabilizes the reference.

Use it when identity stability matters and you have measured or understand the consumer. Avoid wrapping every event handler by default, especially in codebases using React Compiler patterns.

Key Points

• It is mostly useful when passing callbacks to memoized children, using a callback in another hook dependency list, or avoiding resubscription to imperative APIs
• It does not make the function itself faster; it only stabilizes the reference
• Use it when identity stability matters and you have measured or understand the consumer
• For 'What does useCallback do and when should you use it?', the key is to explain what problem the concept solves, where it fits in React's rendering model, and what mistake causes production bugs.

Use it when identity stability matters and you have measured or understand the consumer. Avoid wrapping every event handler by default, especially in codebases using React Compiler patterns

Comparison / Tradeoffs

Use it when identity stability matters and you have measured or understand the consumer. Avoid wrapping every event handler by default, especially in codebases using React Compiler patterns. |

Summary

useCallback caches a function identity between renders while its dependencies stay the same.

Longer Answer

For 'What does useCallback do and when should you use it?', the key is to explain what problem the concept solves, where it fits in React's rendering model, and what mistake causes production bugs.

Use it when identity stability matters and you have measured or understand the consumer. Avoid wrapping every event handler by default, especially in codebases using React Compiler patterns.

Key Points

• For 'What does useCallback do and when should you use it?', the key is to explain what problem the concept solves, where it fits in React's rendering model, and what mistake causes production bugs
• Use it when identity stability matters and you have measured or understand the consumer
• Avoid wrapping every event handler by default, especially in codebases using React Compiler patterns
• Use the answer to connect the concept back to a realistic production or interview scenario for 'What does useCallback do and when should you use it?'

Comparison / Tradeoffs