Разобрали useRef

package-lock.json

@@ -8,7 +8,6 @@
       "name": "store-client",
       "version": "0.0.0",
       "dependencies": {
-        "immer": "^11.1.8",
         "react": "^19.1.0",
         "react-dom": "^19.1.0"
       },
@@ -2055,16 +2054,6 @@
         "node": ">= 4"
       }
     },
-    "node_modules/immer": {
-      "version": "11.1.8",
-      "resolved": "https://registry.npmjs.org/immer/-/immer-11.1.8.tgz",
-      "integrity": "sha512-/tbkHMW7y10Lx6i1crLjD4/OhNkRG+Fo7byZHtah0547nIeXYcpIXaUh0IAQY6gO5459qpGGYapcEOHtFXkIuA==",
-      "license": "MIT",
-      "funding": {
-        "type": "opencollective",
-        "url": "https://opencollective.com/immer"
-      }
-    },
     "node_modules/import-fresh": {
       "version": "3.3.1",
       "resolved": "https://registry.npmjs.org/import-fresh/-/import-fresh-3.3.1.tgz",

package.json

@@ -10,7 +10,6 @@
     "preview": "vite preview"
   },
   "dependencies": {
-    "immer": "^11.1.8",
     "react": "^19.1.0",
     "react-dom": "^19.1.0"
   },

src/App.jsx

@@ -1,49 +1,98 @@
-import React, { useState, useEffect } from 'react'
+import { useState, useRef, useEffect } from 'react'
-import { produce } from 'immer'
 
-function App() {
+function Example() {
-    const [tasks,setTasks] = useState([])
+    const myRef = useRef(null);
-    const [input,setInput] = useState('')
+    const counterRef = useRef(0);
+    const [text, setText] = useState('');
     
-    const addTask = () => {
+    useEffect(() => {
-        if(!input.trim()) return
+        myRef.current?.focus();
+    },[]);
         
-        setTasks(currentTasks => produce(currentTasks, draft => {
+    const handlerFocus = () => {
-            draft.push({
+        if(myRef.current) {
-                id: Date.now(),
+            myRef.current.focus();
-                text: input.trim(),
-                done: false
-            })
-        }))
-        setInput('')
         }
-    const toggleTask = id => {
+    };
-        setTasks(currentTask => produce(currentTask, draft => {
+    
-            const task = draft.find(t => t.id === id)
+    const handlerChange = (event) => {
-            if(task) {
+        setText(event.target.value);
-                task.done = !task.done
     }
-        }))
+    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>
 }
-    const removeTask = id => {
+
-        setTasks(currentTask => produce(currentTask, draft => {
+function ClickCounter() {
-            const index = draft.findIndex(t => t.id === id)
+    const countRef = useRef(0);
-            if (index !== -1)
+    
-                draft.splice(index,1)
+    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 />
+            Предыдущее значение: {prevValueRef.current}
+        </div>
+    )
+}
+
+function ScrollList() {
+    const listRef = useRef(null);
+    
+    const scrollToBottom = () => {
+        if(listRef.current) {
+            listRef.current.scrollTop = listRef.current.scrollHeight;
+        }
+    }
+        
     return (
         <>
-			<h1>Практика по созданию списка задач</h1>
+            <div ref={listRef} 
-            <input value={input} onChange={e=>setInput(e.target.value)} />
+               style={{height: 200, overflowY: 'auto', border: '1px solid black'}}>
-            <button onClick={addTask}>Добавить</button>
+                {[...Array(20)].map((_,i)=>(
-        <ul>{tasks.map(({id,text,done}) => (
+                    <div key={i}>Элемент № {i + 1}</div>
-                <li key={id} style={{ textDecoration: done ? 'line-through' : 'none'}}>
+                ))}
-                <input type="checkbox" checked={done} onChange={()=> toggleTask(id)} />
+            </div>
-                {text}
+            <button onClick={scrollToBottom}>Прокрутить вниз</button>
-                <button onClick={() => removeTask(id)}>Удалить</button>
+        </>
-                </li>
+    )
-            ))}</ul>
+}
+        
+function App() {
+    
+    
+	return (
+		<>
+			<h1>Hello, React!</h1>
+            <ScrollList />
 		</>
 	)
 }

src/MyComponent.jsx

@@ -1,8 +0,0 @@
-export function MyComponent() {
-    return (
-        <>
-        <h1>Hello</h1>
-        </>
-    )
-}
-export default MyComponent