final

src/App.jsx

@@ -1,72 +1,32 @@
-import memo, { useMemo, useCallback, useState } from 'react'
+import React, { useMemo, useCallback, useState } from 'react'
 
-function MyComponent() {
+const TodoItem = React.memo(({ item, onToggle, onDelete }) => {
-    const [count, setCount] = useState(0);
+    console.log(`rendred ${item.id}`);
-    const [name, setName] = useState('John');
+    return <li>
-    
-    const greeting = useMemo(() => `Hello, ${name}!`,[name]);
-    
-    return (
-        <>
-        <h2>{greeting}</h2>
-        <button onClick={()=>setName('Alex')}>New name</button>
-        </>
-    )
-}
-
-function MyComponent2() {
-    const [data,setData] = useState([{theme:'light'}])
-    const userPreferences = useMemo(()=>({theme: 'dark', language: 'en'}),[]);
-    
-    const processData = useMemo(()=>{
-        return data.map(item => ({ ...item,theme: userPreferences.theme }))
-    },[data, userPreferences]);
-    console.log(processData);
-    return (
-        <>
-            <h2 className={data.theme}>2</h2>
-            <button onClick={()=>setData(data)}>set new theme</button>
-        </>
-    )
-}
-
-function MyComponent3() {
-    const sum = useMemo(()=> a+b,[a,b]);//Бессмысленное применение и вредное
-
-    //Применение оправдано
-    const complexResult = useMemo(()=>{
-        return heavyMethOperations(largeDataSet);
-    },[largeDataSet])
-}
-
-function ParentComponent({ items }) {
-    const [filter, setFilter] = useState('');
-    
-    const listProps = useMemo(()=>({
-            items: items.filter(item => item.name.includes(filter)),
-            onItemClick: id => console.log('Clicked',id),
-            theme: 'dark'
-        }),[items,filter]);
-    
-    return (
-        <>
-        <Memoized {...listProps} />
-        <button onClick={()=>setFilter('Bob')}>Click</button>
-        </>
-    )
-}
-
-function Memoized(props) {
-    console.log(props);
-    return (
-        <>
-        <h3 className={props.theme}>Memoized</h3>
-        {props.items.map((item) => (
-         <>
-            <li>
             {item.name}
+            <button onClick={() => onToggle(item.id)}>Done</button>
+            <button onClick={() => onDelete(item.id)}>remove</button>
         </li>
-         </>))}
+})
+
+function ItemList({ items }) {
+
+    const handleToggle = useCallback(id => {
+        items.done = true;
+        console.log(`Item ${id} done`)
+        console.log(id)
+    },[]);
+    
+    const handleDelete = useCallback(id => {
+        items.pop(id);
+    },[]);
+    return (
+        <>
+            <h3>List items</h3>
+            {items.map(item => (
+             <TodoItem key={item.id} item={item}
+              onToggle={handleToggle} onDelete={handleDelete} />
+             ))}
         </>
     )
 }
@@ -76,7 +36,10 @@ function App() {
 		<>
 			{/* Добавьте тестовый контент для проверки */}
 			<h1>Hello, React!</h1>
-            <ParentComponent items={[{name:'Alex'},{name:'Bob'}]} />
+            <ItemList items={[
+                {id:1,name:'Первый',done:false},
+                {id:2,name:'Второй',done:false}
+            ]} />
 		</>
 	)
 }