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Author SHA1 Message Date
laktionov-as 43aeb40b20 i dont know 2026-06-18 18:53:17 +03:00
2 changed files with 34 additions and 70 deletions
+29 -67
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@@ -1,74 +1,33 @@
import memo, { useMemo, useCallback, useState } from 'react' import { useMutation, QueryClientProvider, QueryClient } from '@tanstack/react-query'
import PostAddForm from './components/PostAddForm'
function MyComponent() { /*
const [count, setCount] = useState(0); const mutation = useMutation({
const [name, setName] = useState('John'); mutationFn: newUser => {
fetch('https://jsonplaceholder.typicode.com/users', {
const greeting = useMemo(() => `Hello, ${name}!`,[name]); method: 'GET',
headers: {'Content-type':'application/json'},
return ( body: JSON.stringify(newUser),
<> }).then(res => res.json())
<h2>{greeting}</h2>
<button onClick={()=>setName('Alex')}>New name</button>
</>
)
} }
})
*/
function MyComponent2() { const createQueryClient = () => {
const [data,setData] = useState([{theme:'light'}]) new QueryClient({
const userPreferences = useMemo(()=>({theme: 'dark', language: 'en'}),[]); defaultOptions: {
queries: {
const processData = useMemo(()=>{ staleTime: 5 * 60*1000,
return data.map(item => ({ ...item,theme: userPreferences.theme })) retry: 1,
},[data, userPreferences]); gcTime: 10*60*1000,
console.log(processData); refetchOnWindowFocus: false,
return ( },
<> mutations: {
<h2 className={data.theme}>2</h2> retry:0,
<button onClick={()=>setData(data)}>set new theme</button> onError: error => {console.error('Mutation error:',error.message)}
</>
)
} }
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}
</li>
</>))}
</>
)
} }
function App() { function App() {
@@ -76,7 +35,10 @@ function App() {
<> <>
{/* Добавьте тестовый контент для проверки */} {/* Добавьте тестовый контент для проверки */}
<h1>Hello, React!</h1> <h1>Hello, React!</h1>
<ParentComponent items={[{name:'Alex'},{name:'Bob'}]} /> <QueryClientProvider client={createQueryClient}>
<PostAddForm />
</QueryClientProvider>
</> </>
) )
} }
+2
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@@ -4,5 +4,7 @@ import { createRoot } from 'react-dom/client'
import App from './App.jsx' import App from './App.jsx'
createRoot(document.getElementById('root')).render( createRoot(document.getElementById('root')).render(
<StrictMode>
<App /> <App />
</StrictMode>
) )