Сделали таймер

src/App.jsx

@@ -1,60 +1,109 @@
-import { memo, useState, useMemo } from 'react'
+import React from 'react'
 
-function memoize(fn) {
+class MyComponent extends React.Component {
-    const cache = new Map();
+    constructor(props) {
-    return function(...args) {
+        super(props);
-        const key = JSON.stringify(args);
+        this.state = { data: null };
-        if (cache.has(key)) {
+        this.handleClick = this.handleClick.bind(this);
-            return cache.get(key);
+    }
-        }
+    
-        const result = fn.apply(this, args);
+    render() {
-        cache.set(key,result);
+        return (
-        return result;
+            <div>
+            {this.state.data ? (
+                    <div>Данные: {this.state.data}</div>
+                ) : (
+                    <div>Загрузка...</div>
+                )}
+                <button onClick={this.handleClick}>Обновить</button>
+            </div>
+        )
+    }
+    
+    componentDidMount() {
+        fetch('https://api.example.com/data')
+        .then(responce => responce.json())
+        .then(json => this.setState({data: json}));
+        
+        this.timerId = setInterval(()=> console.log('Tick'), 1000);
+    }
+    
+    componentWillUnmout() {
+        clearInterval(this.timerId);
+    }
+    
+    handleClick() {
+        this.setState({data: 'Данные'})
     }
 }
 
-function fibonachi(n, memo={}) {
+class MyComponent2 extends React.Component {
-    if (n in memo) {console.log(n);return memo[n];}
+    controller = new AbortController()
-    if (n <= 1) return 1;
+
-    memo[n] = fibonachi(n-1, memo) + fibonachi(n - 2, memo);
+    componentDidMount() {
-    return memo[n];
+        fetch('https://api.example.com/data',{ singnal: this.controller.signal })
+        .then(responce => responce.json())
+        .then(json => this.setState({data: json}))
+        .catch(error => {
+            if(error.name == 'AbortError') {
+                console.log('Aborted');
+            } else {
+                console.log('Other error',error);
+            }
+        });
+    }
+
+    componentWillUnmount() {
+        this.controller.abort()
+    }
+}
+class MyComponent3 extends React.Component {
+    componentDidMount() {
+        this.loadData();
+    }
+    
+    async loadData() {
+        try {
+            const response = await fetch('https://api.example.com/data');
+            const data = await response.json();
+            this.setSate({ data });
+        } catch {
+            console.log('error');
+        }
+    }
 }
 
-const MyComponent = ({ value }) => {
+class Timer extends React.Component {
-    console.log('Rendring');
+    constructor(props) {
-    return <div>{value}</div>
+        super(props);
-}
+        this.state = { seconds: 0 }
+    }
     
-const MemoizedComponent = memo(MyComponent);
+    componentDidMount() {
+        console.log('Timer mounted');
+        this.interval = setInterval(()=>{
+            this.setState(prevState => ({seconds: prevState.seconds + 1}))
+        },1000);
+    }
     
-const Child = memo(({ children }) => {
+    componentWillUnmount() {
-    console.log('Child component rendred');
+        console.log('Timer unmount');
-    return <div>{children}</div>;
+        clearInterval(this.interval);
-});
+    }
-
+    render() {
-const Parent = () => {
+        return <h2>Прошло секунд: {this.state.seconds}</h2>
-    const [count,setCount] = useState(0);
+    }
-    const [text, setText] = useState('');
-    
-    const stableChild = useMemo(() => <span>Memo text</span>,[]);
-    
-    return (
-        <>
-            <Child>
-                {stableChild}
-            </Child>
-            <input type="text" onChange={(e) => setText(e.target.value)} value={text} />
-            <button onClick={() => setCount(count + 1)}>Increment {count}</button>
-        </>
-    )
 }
 
 function App() {
+    const [show,setShow] = React.useState(true);
+    
 	return (
 		<>
-			<h1>Hello, React!</h1>
+			<h1>Таймер с классом</h1>
-            <Parent />
+            <button onClick={()=>setShow(prev => !prev)}>{show ? 'Скрыть' : 'Показать'} таймер</button>
-        </>
+            {show && <Timer />}
+		</>
 	)
 }