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src/App.jsx

@@ -1,98 +1,78 @@
-import { useState, useRef, useEffect } from 'react'
+import { useState, createContext, useContext } from 'react'
+import styles from './App.module.scss'
 
-function Example() {
+const UserContext = createContext('')
-    const myRef = useRef(null);
+
-    const counterRef = useRef(0);
+function UserProvider({ children }) {
-    const [text, setText] = useState('');
+    const [name,setName] = useState('');
     
-    useEffect(() => {
+    const toggleName = (newName) => {
-        myRef.current?.focus();
+        setName(newName);
-    },[]);
-        
-    const handlerFocus = () => {
-        if(myRef.current) {
-            myRef.current.focus();
-        }
-    };
-    
-    const handlerChange = (event) => {
-        setText(event.target.value);
     }
-    counterRef.current += 1;
-    return <div>
-        <input ref={myRef} text="text" /><br />
-        Количество рендров: {counterRef.current}<br />
-        <input text="text" onChange={handlerChange} value={text} />
-        <button onClick={handlerFocus}>Поставить фокус на поле</button>
-    </div>
-}
-
-function ClickCounter() {
-    const countRef = useRef(0);
     
-    function handlerClick() {
-        countRef.current += 1;
-        //alert(`Нажали ${countRef.current} раз.`);
-    }
-    return <button onClick={handlerClick}>Нажать</button>;
-}
-
-function TimerComponent() {
-    const timerIdRef = useRef(null);
-    
-    useEffect(() => {
-        timerIdRef.current = setTimeout(() => {
-            alert("Прошло 3 секунды");
-        }, 3000);
-        return () => {
-            clearTimeout(timerIdRef.current);
-        }
-    },[]);
-}
-
-function PrevValue({ value }) {
-    const prevValueRef = useRef();
-    
-    useEffect(() => {
-        prevValueRef.current = value;
-    });
     return (
-        <div>
+        <UserContext.Provider value={{name, toggleName}}>
-            Текущее значение: {value} <br />
+            {children}
-            Предыдущее значение: {prevValueRef.current}
+        </UserContext.Provider>
+    )
+}
+
+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 ScrollList() {
+function Page() {
-    const listRef = useRef(null);
-    
-    const scrollToBottom = () => {
-        if(listRef.current) {
-            listRef.current.scrollTop = listRef.current.scrollHeight;
-        }
-    }
-        
     return (
-        <>
+        <div>
-            <div ref={listRef} 
+            <h1 style={{textAlign: 'center'}}>Главная страница</h1>
-               style={{height: 200, overflowY: 'auto', border: '1px solid black'}}>
+            <Toolbar />
-                {[...Array(20)].map((_,i)=>(
+        </div>
-                    <div key={i}>Элемент № {i + 1}</div>
-                ))}
-            </div>
-            <button onClick={scrollToBottom}>Прокрутить вниз</button>
-        </>
     )
 }
-        
+
-function App() {
+function App() {    
-    
     
 	return (
 		<>
+			{/* Добавьте тестовый контент для проверки */}
 			<h1>Hello, React!</h1>
-            <ScrollList />
+        <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>
 )