Конец урока

src/App.jsx

@@ -1,97 +1,67 @@
-import React from 'react'
-import styles from './App.module.scss'
+import React, { useState, useReducer, useRef, memo } from 'react'
 
-class Clock extends React.Component {
-    constructor(props) {
-        super(props);
-        this.state = { date: new Date() };
-    }
-    componentDidMount() {
-        this.timerId = setInterval( () => this.tick(), 1000);
-    }
-    componentWillUnmount() {
-        clearInterval(this.timerId)
-    }
-    tick() {
-        this.setState({ date: new Date() })
-    }
-    render() {
-        return <div>{this.state.date.toLocaleTimeString()}</div>
+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
     }
 }
 
-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>
-}
+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>
+    )
+})
 
 function App() {
-    const [tracker,setTracker] = React.useState(false);
-    const [dataFetcher,setDataFetcher] = React.useState(false);
+    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()
+    }
     
 	return (
-		<>
-			<h1>Hello, React!</h1>
-            <Clock />
-            <Clock2 />
-            <button onClick={() => setTracker(!tracker)}>Показать/Скрыть трекер</button>
-            { tracker && <MouseTracker /> }
-            <button onClick={() => setDataFetcher(!dataFetcher)}>Показать/Скрыть посты</button>
-            { dataFetcher && <DataFetcher /> }
-		</>
+		<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>
 	)
 }
 

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%;
-    }
-}
-