How React useEffect hook Works

The useEffect hook is a feature in React that allows developers to perform side effects in functional components. Side effects can include data fetching, subscriptions, or manually changing the DOM. The useEffect hook is used to manage these side effects in functional components.

Here’s a basic example of how the useEffect hook works in a React component:

import React, { useState, useEffect } from 'react';

function ExampleComponent() {
  const [count, setCount] = useState(0);

  useEffect(() => {
    document.title = `You clicked ${count} times`;
  });

  return (
    

      
You clicked {count} times
       setCount(count + 1)}>
        Click me
      
    
  );
}
  

In this example, the useEffect hook is used to update the document title whenever the count state changes. The useEffect hook takes a function as its first argument, and an optional array of dependencies as its second argument. If the second argument is not provided, the effect will run after every render. If the second argument is provided, the effect will only run if the values in the array change.

It’s important to note that the useEffect hook can cause performance issues if not used correctly. This is because the effect runs after every render, which can lead to unnecessary re-renders. To optimize the performance of your components, you should provide a second argument to the useEffect hook that specifies the values the effect depends on.

Overall, the useEffect hook is a powerful feature in React that allows developers to manage side effects in functional components. By understanding how the useEffect hook works and using it correctly, you can create efficient and high-performing React applications.