Сделали таймер

src/App.jsx

@@ -1,67 +1,109 @@
-import React, { useState, useReducer, useRef, memo } from 'react'
+import React from 'react'
 
-function tasksReducer(state, action) {
-    switch(action.type) {
-        case 'ADD_TASK':
-            return [...state, action.payload]
-        case 'TOGGLE_TASK':
-            return state.map(task => task.id === action.payload ? {...task, complite: !task.complite} : task)
-        case 'REMOVE_TASK':
-            return state.filter(task => task.id !== action.payload)
-        default:
-            return state
+class MyComponent extends React.Component {
+    constructor(props) {
+        super(props);
+        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() {
+        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'})
     }
 }
 
-const TaskList = memo(function TaskList({tasks, onToggle, onRemove}) {
-    console.log("Rendred")
-    return (
-        <ul>
-        {tasks.map(({id, text, complite}) => (
-                <li key={id}
-                    style={{textDecoration: complite ? 'line-through' : 'none' }}>
-                    <input type="checkbox" checked={complite} onChange={()=>onToggle(id)} />
-                    {text}
-                    <button onClick={()=> onRemove(id)} style={{marginLeft: 10}}>
-                        Удалить
-                    </button>
-                </li>
-            ))}
-        </ul>
-    )
-})
+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() {
+        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');
+        }
+    }
+}
+
+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 <h2>Прошло секунд: {this.state.seconds}</h2>
+    }
+}
 
 function App() {
-    const [tasks, dispatch] = useReducer(tasksReducer,[])
-    const [input,setInput] = useState('')
-    const [error,setError] = useState('')
-    const inputRef = useRef(null)
-    
-    const addTask = () => {
-        if (input.trim() === '') {
-            setError('Пустой текст задачи')
-            return
-        }
-        setError('')
-        dispatch({
-            type: 'ADD_TASK',
-            payload: {id: Date.now(), text: input.trim(), complite: false }
-        })
-        setInput('')
-        inputRef.current.focus()
-    }
+    const [show,setShow] = React.useState(true);
     
 	return (
-		<div style={{padding: 20}}>
-			<h1>Список дел</h1>
-			<input ref={inputRef} value={input} onChange={e => setInput(e.target.value)} />
-			<button onClick={addTask}>Добавить</button>
-            {error && <p style={{color: 'red'}}>{error}</p>}
-            
-            <TaskList tasks={tasks} 
-                onToggle={id => dispatch({type: 'TOGGLE_TASK', payload: id})}
-                onRemove={id => dispatch({type: 'REMOVE_TASK', payload: id})} />
-		</div>
+		<>
+			<h1>Таймер с классом</h1>
+            <button onClick={()=>setShow(prev => !prev)}>{show ? 'Скрыть' : 'Показать'} таймер</button>
+            {show && <Timer />}
+		</>
 	)
 }
 

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>
 )