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3 Commits

Author SHA1 Message Date
laktionov-as 8cc72afd7b final 2026-05-28 19:16:14 +03:00
laktionov-as a520406547 useCallback with React.memo 2026-05-26 21:28:43 +03:00
laktionov-as 38f7195ed4 useCallback 2026-05-26 21:17:42 +03:00
3 changed files with 31 additions and 79 deletions
+29 -62
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@@ -1,78 +1,45 @@
import { useState, createContext, useContext } from 'react' import React, { useMemo, useCallback, useState } from 'react'
import styles from './App.module.scss'
const UserContext = createContext('') const TodoItem = React.memo(({ item, onToggle, onDelete }) => {
console.log(`rendred ${item.id}`);
return <li>
{item.name}
<button onClick={() => onToggle(item.id)}>Done</button>
<button onClick={() => onDelete(item.id)}>remove</button>
</li>
})
function UserProvider({ children }) { function ItemList({ items }) {
const [name,setName] = useState('');
const toggleName = (newName) => { const handleToggle = useCallback(id => {
setName(newName); items.done = true;
} console.log(`Item ${id} done`)
console.log(id)
},[]);
const handleDelete = useCallback(id => {
items.pop(id);
},[]);
return ( return (
<UserContext.Provider value={{name, toggleName}}> <>
{children} <h3>List items</h3>
</UserContext.Provider> {items.map(item => (
) <TodoItem key={item.id} item={item}
} onToggle={handleToggle} onDelete={handleDelete} />
))}
function Form() { </>
const {name, toggleName} = useContext(UserContext)
const [newName,setNewName] = useState('');
const handleSubmit = (event) => {
event.preventDefault();
toggleName(event.target[0].value)
}
const handlerChange = (event) => {
setNewName(event.target.value);
}
return (
<form onSubmit={handleSubmit}>
<input type='text' value={newName} onChange={handlerChange} />
<button type='submit'>Войти</button>
</form>
)
}
function ExitButton() {
const {name, toggleName} = useContext(UserContext)
return (
<button onClick={() => toggleName('')}>Выход</button>
)
}
function Toolbar() {
const {name, toggleName} = useContext(UserContext)
return(
<div className={styles.container}>
<h3>Панель пользователя</h3>
{name && `Привет ${name}`}
{name ? <ExitButton /> : <Form /> }
</div>
)
}
function Page() {
return (
<div>
<h1 style={{textAlign: 'center'}}>Главная страница</h1>
<Toolbar />
</div>
) )
} }
function App() { function App() {
return ( return (
<> <>
{/* Добавьте тестовый контент для проверки */} {/* Добавьте тестовый контент для проверки */}
<h1>Hello, React!</h1> <h1>Hello, React!</h1>
<UserProvider> <ItemList items={[
<Page /> {id:1,name:'Первый',done:false},
</UserProvider> {id:2,name:'Второй',done:false}
]} />
</> </>
) )
} }
-13
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@@ -1,13 +0,0 @@
.container {
height: 500px;
border: 1px solid black;
border-radius: 10px;
background-color: lightblue;
}
.item {
font-size: 16pt;
border: 1px dotted gray;
/*margin: 5px 10px;
padding: 10px;*/
border-radius: 5px;
}
-2
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@@ -4,7 +4,5 @@ import { createRoot } from 'react-dom/client'
import App from './App.jsx' import App from './App.jsx'
createRoot(document.getElementById('root')).render( createRoot(document.getElementById('root')).render(
<StrictMode>
<App /> <App />
</StrictMode>
) )