The difference between useCallback and useMemo in practice lies in what they are used to memoize and their impact on the performance and behavior of React components.
useCallback is a hook that returns a memoized version of a callback function. This means that the function is stored and reused until one of its dependencies changes, as specified in the dependency array. The primary use case for useCallback is to prevent the re-creation of functions that could lead to unnecessary re-renders, especially when the function is passed as a prop to child components. This can be particularly beneficial in performance optimization when dealing with expensive functions or when the function is a dependency for other hooks or child components that rely on reference equality to prevent unnecessary updates[1][2][4][5][6][7].
On the other hand, useMemo is used to memoize a value rather than a function. It accepts a function that returns a value and a list of dependencies, and it will only recompute the memoized value when one of the dependencies has changed. The main purpose of useMemo is to avoid expensive calculations on every render, which can improve performance by preventing unnecessary computations. It is also useful for maintaining referential equality of objects or arrays between renders, which can prevent child components from re-rendering if they depend on these objects or arrays[1][2][3][4][6][7].
In practice, useCallback is often used when you have a function that you don't want to recreate unless its dependencies change, such as an event handler that is passed down to a child component. useMemo, on the other hand, ...
