Сделали таймер

src/App.jsx

@@ -1,96 +1,108 @@
 import React from 'react'
-import styles from './App.module.scss'
 
-class Clock extends React.Component {
+class MyComponent extends React.Component {
     constructor(props) {
         super(props);
-        this.state = { date: new Date() };
+        this.state = { data: null };
+        this.handleClick = this.handleClick.bind(this);
     }
+    
+    render() {
+        return (
+            <div>
+            {this.state.data ? (
+                    <div>Данные: {this.state.data}</div>
+                ) : (
+                    <div>Загрузка...</div>
+                )}
+                <button onClick={this.handleClick}>Обновить</button>
+            </div>
+        )
+    }
+    
     componentDidMount() {
-        this.timerId = setInterval( () => this.tick(), 1000);
+        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'})
+    }
+}
+
+class MyComponent2 extends React.Component {
+    controller = new AbortController()
+
+    componentDidMount() {
+        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() {
-        clearInterval(this.timerId)
+        this.controller.abort()
     }
-    tick() {
+}
-        this.setState({ date: new Date() })
+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');
+        }
+    }
+}
+
+class Timer extends React.Component {
+    constructor(props) {
+        super(props);
+        this.state = { seconds: 0 }
+    }
+    
+    componentDidMount() {
+        console.log('Timer mounted');
+        this.interval = setInterval(()=>{
+            this.setState(prevState => ({seconds: prevState.seconds + 1}))
+        },1000);
+    }
+    
+    componentWillUnmount() {
+        console.log('Timer unmount');
+        clearInterval(this.interval);
     }
     render() {
-        return <div>{this.state.date.toLocaleTimeString()}</div>
+        return <h2>Прошло секунд: {this.state.seconds}</h2>
     }
 }
 
-function Clock2() {
-    const [date, setDate] = React.useState(new Date());
-    
-    React.useEffect(()=>{
-        const timerId = setInterval(()=> setDate(new Date()),1000);
-        return () => clearInterval(timerId);
-    },[])
-    
-    return <div>{date.toLocaleTimeString()}</div>
-}
-
-function MouseTracker() {
-    const [x,setX] = React.useState(0);
-    const [y,setY] = React.useState(0);
-    
-    const mouseMoveHandler = event => {
-        setX(event.clientX);
-        setY(event.clientY);
-    }
-    
-    React.useEffect(()=>{
-        document.addEventListener('mousemove', mouseMoveHandler);
-        return () => {
-            document.removeEventListener('mousemove',mouseMoveHandler);
-        }
-    },[]);
-    
-    return <div className={styles.container}>
-        <p>Координаты мыши:<br /> X:<b>{x}</b>, Y:<b>{y}</b></p>
-        </div>
-}
-
-function DataFetcher() {
-    const [posts,setPosts] = React.useState([]);
-    const [users,setUsers] = React.useState([]);
-    
-    const getPosts = async () => {
-        const response = await fetch('https://jsonplaceholder.typicode.com/posts');
-        const data = await response.json();
-        setUsers(data.reduce((acc, value) => {
-            if (!(value.userId in acc))
-                return [...acc,value.userId]
-            return acc
-        }))
-        console.log(users);
-        setPosts(data.slice(1,10));
-        
-    }
-    
-    React.useEffect(() => {
-        console.log("Компонент создан");
-        getPosts();
-        return () => {console.log("Компонент удален");setPosts([])};
-    },[])
-    
-    return <div><ol>{posts.map(post => <li id={post.id}>{post.title}</li>)}</ol></div>
-}
-
 function App() {
-    const [tracker,setTracker] = React.useState(false);
+    const [show,setShow] = React.useState(true);
-    const [dataFetcher,setDataFetcher] = React.useState(false);
     
 	return (
 		<>
-			<h1>Hello, React!</h1>
+			<h1>Таймер с классом</h1>
-            <Clock />
+            <button onClick={()=>setShow(prev => !prev)}>{show ? 'Скрыть' : 'Показать'} таймер</button>
-            <Clock2 />
+            {show && <Timer />}
-            <button onClick={() => setTracker(!tracker)}>Показать/Скрыть трекер</button>
-            { tracker && <MouseTracker /> }
-            <button onClick={() => setDataFetcher(!dataFetcher)}>Показать/Скрыть посты</button>
-            { dataFetcher && <DataFetcher /> }
 		</>
 	)
 }

src/App.module.scss

@@ -1,11 +0,0 @@
-.container {
-    width: 300px;
-    height: 200px;
-    border: 2px dashed grey;
-    margin: 10px;
-    text-align: center;
-    p {
-        margin-top: 20%;
-    }
-}
-

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>
 )