useCallback

In React, the useCallback hook is used to return a memoized callback function. It is useful when you want to optimize the performance of a component by avoiding unnecessary re-renders.

Here’s a simple example of how to use the useCallback hook:

import { useCallback } from 'react';

function MyComponent(props) {
  const { data } = props;

  // The useCallback hook takes a function and an array of dependencies as arguments
  // and returns a memoized version of the function.
  const memoizedCallback = useCallback(() => {
    // This function will only be re-created if one of the dependencies has changed.
    // Otherwise, the same function instance will be used.
    doSomething(data);
  }, [data]);

  return <div onClick={memoizedCallback}>Click me</div>;
}

In this example, the memoizedCallback function will only be re-created if the data prop has changed. This can help to avoid unnecessary re-renders of the MyComponent component if the memoizedCallback function is passed as a prop to a child component.

useCallback is a hook in React that allows you to memoize a function. This means that the function will only be re-created if one of its dependencies has changed. This can be useful in a number of situations, such as:

1. When you pass a callback prop to a performance-critical child component, and you don’t want the child component to re-render every time the parent re-renders.
2. When you have an expensive operation that you don’t want to perform on every render, such as an API call or a deep object comparison.

Here’s an another example of how you might use useCallback:

const MyComponent = ({ onClick }) => {
  const handleClick = useCallback(() => {
    console.log('clicked');
  }, []);

  return <button onClick={handleClick}>Click me</button>;
};

In this example, the handleClick function will only be re-created if the component re-renders with a different onClick prop.

When to use React useCallback() ?

You should use useCallback when you have a callback function that is passed as a prop to a child component, and that child component should not re-render when the parent component re-renders unless the callback has changed.

For example, when you have a child component that renders a list of items, and the parent component is responsible for handling the delete action, you can use useCallback to create a memoized version of the callback function that is passed as a prop to the child component. This way, the child component only re-renders when the delete action callback changes and not every time the parent component re-renders.

It is also useful when you have a callback function that is computationally expensive and you want to avoid re-creating it on every render.