Сделали React.memo и React.useMemo

src/App.jsx

@@ -1,112 +1,60 @@
-import React from 'react'
+import { memo, useState, useMemo } from 'react'
 
-class ErrorBoundary extends React.Component {
-    constructor(props) {
-        super(props);
-        this.state = {hasError: false};
-    }
-    
-    static getDerivedStateFromError(error) {
-        return { hasError: true }
-    }
-    
-    componentDidCatch(error,info) {
-        console.log(error,info);
-    }
-    
-    handlerReset = () => {
-        this.setState({hasError: false});
-    }
-    
-    render() {
-        if (this.state.hasError) {
-            return (
-                <div>
-                    <h1>Что то поломалось</h1>
-                    <button onClick={this.handlerReset}>Повторить</button>
-                </div>)
+function memoize(fn) {
+    const cache = new Map();
+    return function(...args) {
+        const key = JSON.stringify(args);
+        if (cache.has(key)) {
+            return cache.get(key);
         }
-        return this.props.children;
+        const result = fn.apply(this, args);
+        cache.set(key,result);
+        return result;
     }
 }
 
-class AdvancedErrorBoundary extends React.Component {
-    constructor(props) {
-        super(props);
-        this.state = {
-            hasError: false,
-            error: null,
-            errorInfo: null
-        }
-    }
-    
-    static getDerivedStateFromError(error) {
-        return { hasErorr: true }
-    }
-    
-    componentDidCatch(error, info) {
-        this.setState({ 
-            error: error,
-            errorInfo: info
-        })
-    }
-    
-    handleReset = () => {
-        this.setState({
-            hasError:false,
-            error: null,
-            errorInfo:null
-        });
-    }
-    
-    render() {
-        if(this.state.hasError) {
-            console.log('Error');
-            return (
-                <div>
-                    <h2>Произошла ошибка</h2>
-                    <p>Извеняемся, работаем, исправляем. Разработчика привязали к батарее</p>
-                    <button onClick={this.handleReset}>Попробовать снова</button>
-                </div>
-            )
-        }
-        //Если ошибок нет, то рендрим дочерние объекты
-        return this.props.children
-    }
+function fibonachi(n, memo={}) {
+    if (n in memo) {console.log(n);return memo[n];}
+    if (n <= 1) return 1;
+    memo[n] = fibonachi(n-1, memo) + fibonachi(n - 2, memo);
+    return memo[n];
 }
 
-function ProblemComponent() {
-    const [counter,setCounter] = React.useState(0)
+const MyComponent = ({ value }) => {
+    console.log('Rendring');
+    return <div>{value}</div>
+}
+
+const MemoizedComponent = memo(MyComponent);
+
+const Child = memo(({ children }) => {
+    console.log('Child component rendred');
+    return <div>{children}</div>;
+});
+
+const Parent = () => {
+    const [count,setCount] = useState(0);
+    const [text, setText] = useState('');
     
-    const handlerClick = () => setCounter(counter + 1)
+    const stableChild = useMemo(() => <span>Memo text</span>,[]);
     
-    React.useEffect(() => {
-        if (counter > 5) {
-            throw new Error("Ошибка в компоненте");
-        }
-    },[counter]);
     return (
-        <div>
-            <h2>Счетчик: {counter}</h2>
-            <button onClick={handlerClick}>Прибавить</button>
-        </div>
+        <>
+            <Child>
+                {stableChild}
+            </Child>
+            <input type="text" onChange={(e) => setText(e.target.value)} value={text} />
+            <button onClick={() => setCount(count + 1)}>Increment {count}</button>
+        </>
     )
 }
 
 function App() {
 	return (
 		<>
-			<h1>Обработка ошибок в компонентах</h1>
-            <ErrorBoundary>
-                <ProblemComponent />
-            </ErrorBoundary>
-            <ErrorBoundary>
-                <ProblemComponent />
-            </ErrorBoundary>
-            <ErrorBoundary>
-                <ProblemComponent />
-            </ErrorBoundary>
-		</>
+			<h1>Hello, React!</h1>
+            <Parent />
+        </>
 	)
 }
 

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>
 )