how to create react useeffect code example

Example 1: 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 (
    

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

Example 2: react custom hooks

import React, { useState } from "react";
 
// custom hooks useForm
const useForm = callback => {
  const [values, setValues] = useState({});
  return {
    values,
    onChange: e => {
      setValues({
        ...values,
        [e.target.name]: e.target.value
      });
    },
    onSubmit: e => {
      e.preventDefault();
      callback();
    }
  };
};
 
// app component
export default function App() {
  const { values, onChange, onSubmit } = useForm(() => {
    console.log(values.username);
    console.log(values.email);
  });
  return (
    

      

        
        
        
      
    
  );
}