Сделали useReducer для счетчика

src/App.jsx

@@ -1,98 +1,50 @@
-import { useState, useRef, useEffect } from 'react'
+import { useState, useReducer } from 'react'
 
-function Example() {
+function counterReducer(state, action) {
-    const myRef = useRef(null);
+    switch (action.type) {
-    const counterRef = useRef(0);
+        case 'increment':
-    const [text, setText] = useState('');
+            return state + 1
-    
+        case 'decrement':
-    useEffect(() => {
+            return state - 1
-        myRef.current?.focus();
+        case 'reset':
-    },[]);
+            return 0
-        
+        case 'set_value':
-    const handlerFocus = () => {
+            return action.value
-        if(myRef.current) {
+        default:
-            myRef.current.focus();
+            return state
-        }
-    };
-    
-    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() {
+function Counter() {
-    const countRef = useRef(0);
+    const [count, dispatch] = useReducer(counterReducer,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>
-            Текущее значение: {value} <br />
+            <span>Счетчик: {count}</span>
-            Предыдущее значение: {prevValueRef.current}
+            <button onClick={()=> dispatch({type: 'increment'})}>+</button>
+            <button onClick={()=> dispatch({type: 'decrement'})}>-</button>
+            <button onClick={()=> dispatch({type: 'reset'})}>reset</button>
+            <button onClick={()=> dispatch({type: 'set_value', value: 5})}>set 5</button>
         </div>
     )
 }
 
-function ScrollList() {
-    const listRef = useRef(null);
-    
-    const scrollToBottom = () => {
-        if(listRef.current) {
-            listRef.current.scrollTop = listRef.current.scrollHeight;
-        }
-    }
-        
-    return (
-        <>
-            <div ref={listRef} 
-               style={{height: 200, overflowY: 'auto', border: '1px solid black'}}>
-                {[...Array(20)].map((_,i)=>(
-                    <div key={i}>Элемент № {i + 1}</div>
-                ))}
-            </div>
-            <button onClick={scrollToBottom}>Прокрутить вниз</button>
-        </>
-    )
-}
-        
 function App() {
+    const [tasks, setTasks] = useState([])
+    const [filter, setFilter] = useState('all')
+    const [sortBy,setSortBy] = useState('date')
+    
+    const addTask = newTask => {
+        setTasks([...tasks,newTask])
+    }
+    
     
     
 	return (
 		<>
+			{/* Добавьте тестовый контент для проверки */}
 			<h1>Hello, React!</h1>
-            <ScrollList />
+            <Counter />
 		</>
 	)
 }

src/App.module.scss

@@ -0,0 +1,15 @@
+.container {
+/*    display: flex;
+    flex-direction: column;
+    flex-wrap: nowrap;*/
+    height: 500px;
+    overflow: auto;
+    border: 1px solid black;
+}
+.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>
 )