Compare commits

..

3 Commits

Author SHA1 Message Date
laktionov-as 8cc72afd7b final 2026-05-28 19:16:14 +03:00
laktionov-as a520406547 useCallback with React.memo 2026-05-26 21:28:43 +03:00
laktionov-as 38f7195ed4 useCallback 2026-05-26 21:17:42 +03:00
+28 -42
View File
@@ -1,50 +1,32 @@
import { memo, useState, useMemo } from 'react' import React, { useMemo, useCallback, useState } from 'react'
function memoize(fn) { const TodoItem = React.memo(({ item, onToggle, onDelete }) => {
const cache = new Map(); console.log(`rendred ${item.id}`);
return function(...args) { return <li>
const key = JSON.stringify(args); {item.name}
if (cache.has(key)) { <button onClick={() => onToggle(item.id)}>Done</button>
return cache.get(key); <button onClick={() => onDelete(item.id)}>remove</button>
} </li>
const result = fn.apply(this, args); })
cache.set(key,result);
return result;
}
}
function fibonachi(n, memo={}) { function ItemList({ items }) {
if (n in memo) {console.log(n);return memo[n];}
if (n <= 1) return 1;
memo[n] = fibonachi(n-1, memo) + fibonachi(n - 2, memo);
return memo[n];
}
const MyComponent = ({ value }) => { const handleToggle = useCallback(id => {
console.log('Rendring'); items.done = true;
return <div>{value}</div> console.log(`Item ${id} done`)
} console.log(id)
},[]);
const MemoizedComponent = memo(MyComponent);
const Child = memo(({ children }) => {
console.log('Child component rendred');
return <div>{children}</div>;
});
const Parent = () => {
const [count,setCount] = useState(0);
const [text, setText] = useState('');
const stableChild = useMemo(() => <span>Memo text</span>,[]);
const handleDelete = useCallback(id => {
items.pop(id);
},[]);
return ( return (
<> <>
<Child> <h3>List items</h3>
{stableChild} {items.map(item => (
</Child> <TodoItem key={item.id} item={item}
<input type="text" onChange={(e) => setText(e.target.value)} value={text} /> onToggle={handleToggle} onDelete={handleDelete} />
<button onClick={() => setCount(count + 1)}>Increment {count}</button> ))}
</> </>
) )
} }
@@ -52,8 +34,12 @@ const Parent = () => {
function App() { function App() {
return ( return (
<> <>
{/* Добавьте тестовый контент для проверки */}
<h1>Hello, React!</h1> <h1>Hello, React!</h1>
<Parent /> <ItemList items={[
{id:1,name:'Первый',done:false},
{id:2,name:'Второй',done:false}
]} />
</> </>
) )
} }