The useCallback hook in React is used to memoize functions, which means it returns a memoized version of the callback function that only changes if one of the dependencies has changed. Its primary purpose is to optimize performance by avoiding unnecessary re-renders in components that rely on callback functions as dependencies.

Syntax:

const memoizedCallback = useCallback(
    () => {
        doSomething(a, b);
    },
    [a, b],
);

Purpose of useCallback:

• Preventing Unnecessary Renders: In React, when a component re-renders, all functions defined within it are recreated. If a callback function is passed down to child components as a prop, and it’s recreated on every render of the parent component, it can lead to unnecessary re-renders of the child components, even if the callback function’s logic hasn’t changed.
• Optimizing Performance: By memoizing callback functions, useCallback can improve performance, especially in scenarios where callback functions are passed to child components or are dependencies of other hooks like useEffect. When a function is memoized with useCallback, React only recreates it if any of the dependencies specified in the dependency array have changed.