When should we use the useEffect hook?

The useEffect hook in React is used to perform side effects in functional components. Side effects are actions that happen outside of the normal flow of the component, such as fetching data from an API, subscribing to events, or updating the DOM.

When should we use the useEffect hook?

• Data Fetching:
  • If your component needs to fetch data from an external source, such as an API, database, or local storage, useEffect is a good choice. You can use it to initiate the data fetching operation when the component mounts or when certain dependencies change.
• Subscriptions and Event Listeners:
  • If your component needs to subscribe to events, such as keyboard events, mouse events, or WebSocket events, useEffect is useful. You can use it to set up event listeners when the component mounts and clean them up when the component unmounts.
• DOM Manipulation:
  • If your component needs to interact with the DOM, such as updating the title of the document, adding or removing classes from elements, or setting up animations, useEffect is appropriate. You can use it to perform DOM manipulation after the component has been rendered.
• Setting up Timers or Intervals:
  • If your component needs to perform actions at regular intervals, such as polling for updates or implementing a countdown timer, useEffect can be used. You can use it to set up timers or intervals when the component mounts and clear them when the component unmounts.
• Dependency Changes:
  • If you need to run code in response to changes in certain dependencies, such as state variables or props, useEffect is handy. You can specify the dependencies as an array in the second argument of useEffect, and the effect will be re-run whenever any of those dependencies change.

useEffect is used in functional components to handle side effects and perform tasks that are not directly related to rendering UI, such as data fetching, event handling, and DOM manipulation. It’s a versatile hook that allows you to add behavior to your components in a declarative and easy-to-understand way.