import { useState, useEffect } from 'react';

function useFetch(url) {
  const [data, setData] = useState([]);
  const [isLoading, setIsLoading] = useState(true);
  const [error, setError] = useState(null);
  useEffect(() => {
    async function fetchData() {
      try {
        const response = await fetch(url);
        const result = await response.json();
...

import dayjs from 'dayjs';

function formatDate(date) {
  return dayjs(date).format('MM/DD/YYYY');
}

import { useState } from 'react';

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

const [name, setName] = useState('Alice');        // строка
const [isActive, setIsActive] = useState(false);  // булево
const [user, setUser] = useState({ id: 1, name: 'Bob' }); // объект
const [items, setItems] = useState([]);           // массив

setCount(count + 1);
setName('Charlie');
setIsActive(!isActive);
setUser({ ...user, name: 'David' });
setItems([...items, 'New']);

setCount(prev => prev + 1);

function MyComponent() {
  const [count, setCount] = useState(0);
  const [text, setText] = useState('');

  return (
    <>
      <button onClick={() => setCount(count + 1)}>+1</button>
      <input value={text} onChange={e => setText(e.target.value)} />
      <p>Счётчик: {count}</p>
      <p>Текст: {text}</p>
    </>
  );
}