Разобрали useRef

package-lock.json

@@ -9,9 +9,7 @@
       "version": "0.0.0",
       "dependencies": {
         "react": "^19.1.0",
-        "react-dom": "^19.1.0",
+        "react-dom": "^19.1.0"
-        "react-error-boundary": "^6.1.2",
-        "react-router-dom": "^7.17.0"
       },
       "devDependencies": {
         "@eslint/js": "^9.25.0",
@@ -1602,19 +1600,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/cookie": {
-      "version": "1.1.1",
-      "resolved": "https://registry.npmjs.org/cookie/-/cookie-1.1.1.tgz",
-      "integrity": "sha512-ei8Aos7ja0weRpFzJnEA9UHJ/7XQmqglbRwnf2ATjcB9Wq874VKH9kfjjirM6UhU2/E5fFYadylyhFldcqSidQ==",
-      "license": "MIT",
-      "engines": {
-        "node": ">=18"
-      },
-      "funding": {
-        "type": "opencollective",
-        "url": "https://opencollective.com/express"
-      }
-    },
     "node_modules/cross-spawn": {
       "version": "7.0.6",
       "resolved": "https://registry.npmjs.org/cross-spawn/-/cross-spawn-7.0.6.tgz",
@@ -2476,15 +2461,6 @@
         "react": "^19.1.0"
       }
     },
-    "node_modules/react-error-boundary": {
-      "version": "6.1.2",
-      "resolved": "https://registry.npmjs.org/react-error-boundary/-/react-error-boundary-6.1.2.tgz",
-      "integrity": "sha512-3DpCr5HVdZ0caUjYE/kIHBEJN0mNP3ZCgf16c48uJ5TbWjorKVp+YG8W3XqlJ7vJAVNw6wNIImyPXmFydwmyng==",
-      "license": "MIT",
-      "peerDependencies": {
-        "react": "^18.0.0 || ^19.0.0"
-      }
-    },
     "node_modules/react-refresh": {
       "version": "0.17.0",
       "resolved": "https://registry.npmjs.org/react-refresh/-/react-refresh-0.17.0.tgz",
@@ -2495,44 +2471,6 @@
         "node": ">=0.10.0"
       }
     },
-    "node_modules/react-router": {
-      "version": "7.17.0",
-      "resolved": "https://registry.npmjs.org/react-router/-/react-router-7.17.0.tgz",
-      "integrity": "sha512-FDELK7rTMlCHO5+reyXsPlmfr7N1F91lPHsWYfMEGQm/KQ+F4JFM8jGoeQDmDvdTs93Fw9aSilH+uKRb4/jXvQ==",
-      "license": "MIT",
-      "dependencies": {
-        "cookie": "^1.0.1",
-        "set-cookie-parser": "^2.6.0"
-      },
-      "engines": {
-        "node": ">=20.0.0"
-      },
-      "peerDependencies": {
-        "react": ">=18",
-        "react-dom": ">=18"
-      },
-      "peerDependenciesMeta": {
-        "react-dom": {
-          "optional": true
-        }
-      }
-    },
-    "node_modules/react-router-dom": {
-      "version": "7.17.0",
-      "resolved": "https://registry.npmjs.org/react-router-dom/-/react-router-dom-7.17.0.tgz",
-      "integrity": "sha512-fyU2yjGups/hE6Xz0I5ZYbVL8Gx29eCjgpHaRaTaVU+OOAdfRX05KsvyRm0GO8YQwOkhpU3MurW1jyMUJn+zSw==",
-      "license": "MIT",
-      "dependencies": {
-        "react-router": "7.17.0"
-      },
-      "engines": {
-        "node": ">=20.0.0"
-      },
-      "peerDependencies": {
-        "react": ">=18",
-        "react-dom": ">=18"
-      }
-    },
     "node_modules/resolve-from": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/resolve-from/-/resolve-from-4.0.0.tgz",
@@ -2606,12 +2544,6 @@
         "semver": "bin/semver.js"
       }
     },
-    "node_modules/set-cookie-parser": {
-      "version": "2.7.2",
-      "resolved": "https://registry.npmjs.org/set-cookie-parser/-/set-cookie-parser-2.7.2.tgz",
-      "integrity": "sha512-oeM1lpU/UvhTxw+g3cIfxXHyJRc/uidd3yK1P242gzHds0udQBYzs3y8j4gCCW+ZJ7ad0yctld8RYO+bdurlvw==",
-      "license": "MIT"
-    },
     "node_modules/shebang-command": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/shebang-command/-/shebang-command-2.0.0.tgz",

package.json

@@ -11,9 +11,7 @@
   },
   "dependencies": {
     "react": "^19.1.0",
-    "react-dom": "^19.1.0",
+    "react-dom": "^19.1.0"
-    "react-error-boundary": "^6.1.2",
-    "react-router-dom": "^7.17.0"
   },
   "devDependencies": {
     "@eslint/js": "^9.25.0",

src/App.jsx

@@ -1,25 +1,98 @@
-import { Suspense, lazy } from 'react'
+import { useState, useRef, useEffect } from 'react'
-import { ErrorBoundary } from 'react-error-boundary'
 
-const LazyComponent = lazy(() => import('./MyComponent'))
+function Example() {
+    const myRef = useRef(null);
+    const counterRef = useRef(0);
+    const [text, setText] = useState('');
     
-function ErrorFallBack({error, resetErrorBoundary }) {
+    useEffect(() => {
+        myRef.current?.focus();
+    },[]);
+        
+    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>
-            <h2>Что то сломалось</h2>
+            Текущее значение: {value} <br />
-            <button onClick={resetErrorBoundary}></button>
+            Предыдущее значение: {prevValueRef.current}
         </div>
     )
 }
 
-function App() {
+function ScrollList() {
+    const listRef = useRef(null);
+    
+    const scrollToBottom = () => {
+        if(listRef.current) {
+            listRef.current.scrollTop = listRef.current.scrollHeight;
+        }
+    }
+        
     return (
         <>
-			<ErrorBoundary FallBackComponent={ErrorFallBack}>
+            <div ref={listRef} 
-                <Suspense fallback={<div>Загрузка ...</div>}>
+               style={{height: 200, overflowY: 'auto', border: '1px solid black'}}>
-			        <LazyComponent />
+                {[...Array(20)].map((_,i)=>(
-                </Suspense>
+                    <div key={i}>Элемент № {i + 1}</div>
-            </ErrorBoundary>
+                ))}
+            </div>
+            <button onClick={scrollToBottom}>Прокрутить вниз</button>
+        </>
+    )
+}
+        
+function App() {
+    
+    
+	return (
+		<>
+			<h1>Hello, React!</h1>
+            <ScrollList />
 		</>
 	)
 }

src/main.jsx

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