What's the difference between useCallback and useMemo in practice?W...

In practice, the primary difference between useCallback and useMemo in React.js lies in what they are used to memoize and their typical use cases within a component's rendering behavior.

useCallback

useCallback is a hook that returns a memoized version of a callback function. This hook is particularly useful when you need to pass callback functions down to child components as props. By memoizing the function, useCallback ensures that the function's identity remains consistent across renders unless its dependencies change. This stability in function identity helps in preventing unnecessary re-renders of child components that rely on these functions as props, thus optimizing performance.

For example, if a parent component passes a click handler to a child component and the handler is defined using useCallback, the child component will not unnecessarily re-render just because the parent component re-renders. The memoized function only changes if its dependencies change[1][2].

useMemo

On the other hand, useMemo is used to memoize expensive calculations or values. This hook takes a function that returns a value and an array of dependencies. useMemo will only recompute the memoized value when one of the dependencies has changed. This is particularly useful when you have computationally expensive operations that should not be run on every render but only when specific data changes.

For instance, if you are calculating an aggregated value from a large dataset, you can use useMemo to ensure that this calculation is only performed when the dataset changes, not on every render. This prevents unnecessary computations and optimizes performance by reducing the load during render...