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| Author | SHA1 | Date | |
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| 43aeb40b20 |
+32
-70
@@ -1,74 +1,33 @@
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import memo, { useMemo, useCallback, useState } from 'react'
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import { useMutation, QueryClientProvider, QueryClient } from '@tanstack/react-query'
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import PostAddForm from './components/PostAddForm'
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function MyComponent() {
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const [count, setCount] = useState(0);
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const [name, setName] = useState('John');
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/*
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const mutation = useMutation({
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mutationFn: newUser => {
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fetch('https://jsonplaceholder.typicode.com/users', {
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method: 'GET',
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headers: {'Content-type':'application/json'},
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body: JSON.stringify(newUser),
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}).then(res => res.json())
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}
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})
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*/
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const greeting = useMemo(() => `Hello, ${name}!`,[name]);
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return (
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<>
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<h2>{greeting}</h2>
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<button onClick={()=>setName('Alex')}>New name</button>
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</>
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)
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}
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function MyComponent2() {
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const [data,setData] = useState([{theme:'light'}])
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const userPreferences = useMemo(()=>({theme: 'dark', language: 'en'}),[]);
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const processData = useMemo(()=>{
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return data.map(item => ({ ...item,theme: userPreferences.theme }))
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},[data, userPreferences]);
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console.log(processData);
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return (
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<>
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<h2 className={data.theme}>2</h2>
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<button onClick={()=>setData(data)}>set new theme</button>
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</>
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)
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}
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function MyComponent3() {
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const sum = useMemo(()=> a+b,[a,b]);//Бессмысленное применение и вредное
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//Применение оправдано
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const complexResult = useMemo(()=>{
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return heavyMethOperations(largeDataSet);
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},[largeDataSet])
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}
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function ParentComponent({ items }) {
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const [filter, setFilter] = useState('');
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const listProps = useMemo(()=>({
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items: items.filter(item => item.name.includes(filter)),
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onItemClick: id => console.log('Clicked',id),
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theme: 'dark'
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}),[items,filter]);
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return (
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<>
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<Memoized {...listProps} />
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<button onClick={()=>setFilter('Bob')}>Click</button>
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</>
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)
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}
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function Memoized(props) {
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console.log(props);
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return (
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<>
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<h3 className={props.theme}>Memoized</h3>
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{props.items.map((item) => (
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<>
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<li>
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{item.name}
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</li>
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</>))}
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</>
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)
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const createQueryClient = () => {
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new QueryClient({
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defaultOptions: {
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queries: {
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staleTime: 5 * 60*1000,
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retry: 1,
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gcTime: 10*60*1000,
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refetchOnWindowFocus: false,
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},
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mutations: {
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retry:0,
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onError: error => {console.error('Mutation error:',error.message)}
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}
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}
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})
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}
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function App() {
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@@ -76,7 +35,10 @@ function App() {
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<>
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{/* Добавьте тестовый контент для проверки */}
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<h1>Hello, React!</h1>
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<ParentComponent items={[{name:'Alex'},{name:'Bob'}]} />
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<QueryClientProvider client={createQueryClient}>
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<PostAddForm />
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</QueryClientProvider>
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</>
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)
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}
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@@ -4,5 +4,7 @@ import { createRoot } from 'react-dom/client'
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import App from './App.jsx'
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createRoot(document.getElementById('root')).render(
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<StrictMode>
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<App />
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</StrictMode>
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)
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