Я уже не помню что там было

src/App.jsx

@@ -1,82 +1,78 @@
-import memo, { useMemo, useCallback, useState } from 'react'
+import { useState, createContext, useContext } from 'react'
+import styles from './App.module.scss'
 
-function MyComponent() {
+const UserContext = createContext('')
-    const [count, setCount] = useState(0);
+
-    const [name, setName] = useState('John');
+function UserProvider({ children }) {
+    const [name,setName] = useState('');
     
-    const greeting = useMemo(() => `Hello, ${name}!`,[name]);
+    const toggleName = (newName) => {
+        setName(newName);
+    }
     
     return (
-        <>
+        <UserContext.Provider value={{name, toggleName}}>
-        <h2>{greeting}</h2>
+            {children}
-        <button onClick={()=>setName('Alex')}>New name</button>
+        </UserContext.Provider>
-        </>
     )
 }
 
-function MyComponent2() {
+function Form() {
-    const [data,setData] = useState([{theme:'light'}])
+    const {name, toggleName} = useContext(UserContext)
-    const userPreferences = useMemo(()=>({theme: 'dark', language: 'en'}),[]);
+    const [newName,setNewName] = useState('');
-    
+    const handleSubmit = (event) => {
-    const processData = useMemo(()=>{
+        event.preventDefault();
-        return data.map(item => ({ ...item,theme: userPreferences.theme }))
+        toggleName(event.target[0].value)
-    },[data, userPreferences]);
+    }
-    console.log(processData);
+    const handlerChange = (event) => {
+        setNewName(event.target.value);
+    }
     return (
-        <>
+        <form onSubmit={handleSubmit}>
-            <h2 className={data.theme}>2</h2>
+        <input type='text' value={newName} onChange={handlerChange} />
-            <button onClick={()=>setData(data)}>set new theme</button>
+        <button type='submit'>Войти</button>
-        </>
+        </form>
     )
 }
 
-function MyComponent3() {
+function ExitButton() {
-    const sum = useMemo(()=> a+b,[a,b]);//Бессмысленное применение и вредное
+    const {name, toggleName} = useContext(UserContext)
-
-    //Применение оправдано
-    const complexResult = useMemo(()=>{
-        return heavyMethOperations(largeDataSet);
-    },[largeDataSet])
-}
-
-function ParentComponent({ items }) {
-    const [filter, setFilter] = useState('');
-    
-    const listProps = useMemo(()=>({
-            items: items.filter(item => item.name.includes(filter)),
-            onItemClick: id => console.log('Clicked',id),
-            theme: 'dark'
-        }),[items,filter]);
     
     return (
-        <>
+        <button onClick={() => toggleName('')}>Выход</button>
-        <Memoized {...listProps} />
-        <button onClick={()=>setFilter('Bob')}>Click</button>
-        </>
     )
 }
 
-function Memoized(props) {
+function Toolbar() {
-    console.log(props);
+    const {name, toggleName} = useContext(UserContext)
-    return (
+    return(
-        <>
+        <div className={styles.container}>
-        <h3 className={props.theme}>Memoized</h3>
+            <h3>Панель пользователя</h3>
-        {props.items.map((item) => (
+            {name && `Привет ${name}`}
-         <>
+            {name ? <ExitButton /> : <Form /> }
-            <li>
+            
-                {item.name}
+        </div>
-            </li>
-         </>))}
-        </>
     )
 }
 
-function App() {
+function Page() {
+    return (
+        <div>
+            <h1 style={{textAlign: 'center'}}>Главная страница</h1>
+            <Toolbar />
+        </div>
+    )
+}
+
+function App() {    
+    
 	return (
 		<>
 			{/* Добавьте тестовый контент для проверки */}
 			<h1>Hello, React!</h1>
-            <ParentComponent items={[{name:'Alex'},{name:'Bob'}]} />
+        <UserProvider>
+            <Page />
+        </UserProvider>
 		</>
 	)
 }

src/App.module.scss

@@ -0,0 +1,13 @@
+.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;
+}

src/main.jsx

@@ -4,5 +4,7 @@ import { createRoot } from 'react-dom/client'
 import App from './App.jsx'
 
 createRoot(document.getElementById('root')).render(
+	<StrictMode>
 		<App />
+	</StrictMode>
 )