In React, the hooks useCallback, useMemo, and useEffect serve distinct purposes, each optimizing different aspects of component behavior and performance. Understanding when and how to use these hooks is crucial for writing efficient and effective React components.
useCallback
useCallback is used to memoize functions. This hook returns a memoized version of the callback function that only changes if one of the dependencies has changed. It is useful when passing callbacks to optimized child components that rely on reference equality to prevent unnecessary renders.
When to use useCallback:
When you pass a callback to a component that is optimized with React.memo or shouldComponentUpdate.
When a callback is used as a dependency in other hooks like useEffect or another useCallback to ensure stability in the dependency array[3][11].
useMemo
useMemo is used to memoize values. This hook returns a memoized value that only recalculates when one of its dependencies changes. It is primarily used to optimize performance by avoiding expensive calculations on every render.
When to use useMemo:
For expensive calculations that are dependent on specific inputs and do not need to be recalculated on every render unless the inputs change[2][9][15].
When you need to pass a complex calculated value to a child component and want to avoid recalculating it unless necessary, especially if the child component renders frequently or is expensive to render[9][15].
useEffect
useEffect is used to perform side effects in function components. Side effects are operations that can affect other components or cannot be done during rendering, such as data fetching, subscriptions, or manually manipulating the DOM.
When to use useEffect:
To interact with external APIs or perform asynchronous operations like data fetching[1][2][6][8].
For setting up subscriptions and listeners, and equally important, cleaning them up to prevent memory leaks. This is done using the cleanup function returned by useEffect[1][6][16].
To perform actions in response to state or prop changes by specifying them in the dependency array. If no dependencies are p...
