reactjs when to use useeffect code example

Example 1: useeffect react

useEffect(() => {
	//  code goes here
    return () => {
      // cleanup code codes here
    };
  },[]);

Example 2: react useeffect

import React, { useState, useEffect } from 'react';
function Example() {
  const [count, setCount] = useState(0);

  // Similar to componentDidMount and componentDidUpdate:  useEffect(() => {    // Update the document title using the browser API    document.title = `You clicked ${count} times`;  });
  return (
    <div>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>
        Click me
      </button>
    </div>
  );
}

Example 3: useEffectOnce

import {useEffectOnce} from 'react-use';

const Demo = () => {
  useEffectOnce(() => {
    console.log('Running effect once on mount')
    
    return () => {
      console.log('Running clean-up of effect on unmount')
    }
  });

  return null;
};