What could be the reasons for un-necessary re-renders in React

Unnecessary re-renders in components can occur due to several reasons, and it’s important to optimize your code to minimize them for better performance.

Here are some common reasons for unnecessary re-renders in functional components:

• Using inline functions in JSX props: If you pass an inline function as a prop to child components, those components will get re-rendered every time the parent component re-renders. This is because a new function is created on every render. You can optimize this by using useCallback hook to memoize the function.
• Using useState hook with objects: If you use useState hook with objects, you need to make sure that you are not mutating the object. If you mutate the object, React will not be able to detect the change and will not re-render the component. You can optimize this by using useReducer hook instead of useState hook.
• Using useEffect hook without dependencies: If you use useEffect hook without dependencies, it will run on every render. You can optimize this by passing an empty array as the second argument to useEffect hook.
• Parent Component Re-renders: If a parent component re-renders, all its child components will also re-render. You can optimize this by using React.memo to memoize the child component where possible.
• Global State Changes: If you use global state management libraries like Redux, MobX, etc., and the global state changes, all the components that use that state will re-render. You can optimize this by using useSelector hook to select only the state that you need in a component.
• Misusing Context: If you use Context API to pass data to child components, and the data changes, all the child components will re-render. You can optimize this by using useContext hook to select only the data that you need in a component.

You can also use React.StrictMode to detect potential problems in your code that could cause unnecessary re-renders.