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3 Commits
| Author | SHA1 | Date | |
|---|---|---|---|
| 6827c800f1 | |||
| 5ee1bf2eee | |||
| c137c644e3 |
+49
-50
@@ -1,60 +1,59 @@
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import { memo, useState, useMemo } from 'react'
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import React from 'react'
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function memoize(fn) {
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const cache = new Map();
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return function(...args) {
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const key = JSON.stringify(args);
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if (cache.has(key)) {
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return cache.get(key);
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}
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const result = fn.apply(this, args);
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cache.set(key,result);
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return result;
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class RandomUser extends React.Component {
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constructor(props) {
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super(props)
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this.state = { user: {} }
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}
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componentDidMount() {
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fetch('https://randomuser.me/api')
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.then(responce => responce.json())
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.then(json => this.setState({ user: json.results[0] }));
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console.log('смонтирован')
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}
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componentDidUpdate(prevProps,prevState) {
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console.log(this.state);
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console.log('Компонент обнвлен')
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}
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componentWillUnmount() {
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console.log('Компонент таймера размонтирован')
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}
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render() {
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return <div>
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{this.state.user &&
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this.state.user.name &&
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(
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<>
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<h2>{this.state.user.name.first} {this.state.user.name.last}</h2>
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<img src={this.state.user.picture.medium} />
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<button onClick={() => {
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console.log('Загружаем ... ')
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fetch('https://randomuser.me/api')
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.then(responce => responce.json())
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.then(json => this.setState({ user: json.results[0] }));
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}}>Загрузить нового</button>
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</>
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)
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}
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</div>
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}
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}
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function fibonachi(n, memo={}) {
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if (n in memo) {console.log(n);return memo[n];}
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if (n <= 1) return 1;
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memo[n] = fibonachi(n-1, memo) + fibonachi(n - 2, memo);
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return memo[n];
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}
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const MyComponent = ({ value }) => {
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console.log('Rendring');
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return <div>{value}</div>
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}
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const MemoizedComponent = memo(MyComponent);
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const Child = memo(({ children }) => {
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console.log('Child component rendred');
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return <div>{children}</div>;
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});
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const Parent = () => {
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const [count,setCount] = useState(0);
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const [text, setText] = useState('');
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const stableChild = useMemo(() => <span>Memo text</span>,[]);
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return (
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<>
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<Child>
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{stableChild}
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</Child>
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<input type="text" onChange={(e) => setText(e.target.value)} value={text} />
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<button onClick={() => setCount(count + 1)}>Increment {count}</button>
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</>
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)
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}
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function App() {
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const [showClock, setShowClock] = React.useState(true);
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return (
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<>
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<h1>Hello, React!</h1>
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<Parent />
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</>
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<h1>Домашнее задание: жизненый цикл</h1>
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<button onClick={()=> setShowClock(!showClock)}>
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{showClock ? 'Скрыть часы' : 'Показать часы' }
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</button>
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{showClock && <RandomUser />}
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</>
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)
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}
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