Answers for "where to declare useeffect"

how to use 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>
  );
}

what does useeffect do

If you’re familiar with React class lifecycle methods, 
you can think of useEffect Hook as componentDidMount, 
componentDidUpdate, and componentWillUnmount combined.