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3 changed files with 52 additions and 44 deletions
+34 -43
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@@ -1,59 +1,50 @@
import { memo, useState, useMemo } from 'react' import { useState, useReducer } from 'react'
function memoize(fn) { function counterReducer(state, action) {
const cache = new Map(); switch (action.type) {
return function(...args) { case 'increment':
const key = JSON.stringify(args); return state + 1
if (cache.has(key)) { case 'decrement':
return cache.get(key); return state - 1
} case 'reset':
const result = fn.apply(this, args); return 0
cache.set(key,result); case 'set_value':
return result; return action.value
default:
return state
} }
} }
function fibonachi(n, memo={}) { function Counter() {
if (n in memo) {console.log(n);return memo[n];} const [count, dispatch] = useReducer(counterReducer,0);
if (n <= 1) return 1;
memo[n] = fibonachi(n-1, memo) + fibonachi(n - 2, memo);
return memo[n];
}
const MyComponent = ({ value }) => {
console.log('Rendring');
return <div>{value}</div>
}
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>,[]);
return ( return (
<> <div>
<Child> <span>Счетчик: {count}</span>
{stableChild} <button onClick={()=> dispatch({type: 'increment'})}>+</button>
</Child> <button onClick={()=> dispatch({type: 'decrement'})}>-</button>
<input type="text" onChange={(e) => setText(e.target.value)} value={text} /> <button onClick={()=> dispatch({type: 'reset'})}>reset</button>
<button onClick={() => setCount(count + 1)}>Increment {count}</button> <button onClick={()=> dispatch({type: 'set_value', value: 5})}>set 5</button>
</> </div>
) )
} }
function App() { function App() {
const [tasks, setTasks] = useState([])
const [filter, setFilter] = useState('all')
const [sortBy,setSortBy] = useState('date')
const addTask = newTask => {
setTasks([...tasks,newTask])
}
return ( return (
<> <>
{/* Добавьте тестовый контент для проверки */}
<h1>Hello, React!</h1> <h1>Hello, React!</h1>
<Parent /> <Counter />
</> </>
) )
} }
+15
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@@ -0,0 +1,15 @@
.container {
/* display: flex;
flex-direction: column;
flex-wrap: nowrap;*/
height: 500px;
overflow: auto;
border: 1px solid black;
}
.item {
font-size: 16pt;
border: 1px dotted gray;
/*margin: 5px 10px;
padding: 10px;*/
border-radius: 5px;
}
+2
View File
@@ -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>
) )