Разобрали useRef

2026-05-21 20:34:06 +03:00
7 changed files with 87 additions and 209 deletions
@@ -5,19 +5,6 @@
 		<link rel="icon" type="image/svg+xml" href="/vite.svg" />
 		<meta name="viewport" content="width=device-width, initial-scale=1.0" />
 		<title>Vite + React</title>
 		<style>
 			* {
 				margin: 0;
 				padding: 0;
 				box-sizing: border-box;
 				font-family: Arial, Helvetica, sans-serif;
 			}
 			body {
 				background-color: #ecfeff;
 			}
 		</style>
 	</head>
 	<body>
 		<div id="root"></div>
@@ -9,8 +9,7 @@
      "version": "0.0.0",
      "dependencies": {
        "react": "^19.1.0",
-        "react-dom": "^19.1.0",
+        "react-dom": "^19.1.0"
        "react-icons": "^5.6.0"
      },
      "devDependencies": {
        "@eslint/js": "^9.25.0",
@@ -2462,15 +2461,6 @@
        "react": "^19.1.0"
      }
    },
    "node_modules/react-icons": {
      "version": "5.6.0",
      "resolved": "https://registry.npmjs.org/react-icons/-/react-icons-5.6.0.tgz",
      "integrity": "sha512-RH93p5ki6LfOiIt0UtDyNg/cee+HLVR6cHHtW3wALfo+eOHTp8RnU2kRkI6E+H19zMIs03DyxUG/GfZMOGvmiA==",
      "license": "MIT",
      "peerDependencies": {
        "react": "*"
      }
    },
    "node_modules/react-refresh": {
      "version": "0.17.0",
      "resolved": "https://registry.npmjs.org/react-refresh/-/react-refresh-0.17.0.tgz",
@@ -4,15 +4,14 @@
  "version": "0.0.0",
  "type": "module",
  "scripts": {
-    "dev": "vite",
+    "dev": "vite", 
    "build": "vite build",
    "lint": "eslint .",
    "preview": "vite preview"
  },
  "dependencies": {
    "react": "^19.1.0",
-    "react-dom": "^19.1.0",
+    "react-dom": "^19.1.0"
    "react-icons": "^5.6.0"
  },
  "devDependencies": {
    "@eslint/js": "^9.25.0",
@@ -1,72 +1,98 @@
-import styles from './App.module.css'
+import { useState, useRef, useEffect } from 'react'
 import SneakersImage from './assets/images/sneakers-image.jpg'
 import { FaRegUser } from 'react-icons/fa'
-function handleClick(i) {
+function Example() {
-    console.log(i);
+    const myRef = useRef(null);
    const counterRef = useRef(0);
    const [text, setText] = useState('');
    useEffect(() => {
        myRef.current?.focus();
    },[]);
    const handlerFocus = () => {
        if(myRef.current) {
            myRef.current.focus();
        }
    };
    const handlerChange = (event) => {
        setText(event.target.value);
    }
    counterRef.current += 1;
    return <div>
        <input ref={myRef} text="text" /><br />
        Количество рендров: {counterRef.current}<br />
        <input text="text" onChange={handlerChange} value={text} />
        <button onClick={handlerFocus}>Поставить фокус на поле</button>
    </div>
 }
-function Header() {
+function ClickCounter() {
-    const handleChange = event => {
+    const countRef = useRef(0);
-        const newValue = event.target.value;
+    
-        console.log(`Новое значение ${newValue}`);
+    function handlerClick() {
        countRef.current += 1;
        //alert(`Нажали ${countRef.current} раз.`);
    }
    return <button onClick={handlerClick}>Нажать</button>;
 }
 function TimerComponent() {
    const timerIdRef = useRef(null);
    useEffect(() => {
        timerIdRef.current = setTimeout(() => {
            alert("Прошло 3 секунды");
        }, 3000);
        return () => {
            clearTimeout(timerIdRef.current);
        }
    },[]);
 }
 function PrevValue({ value }) {
    const prevValueRef = useRef();
    useEffect(() => {
        prevValueRef.current = value;
    });
    return (
-		<header className={styles.header}>
+        <div>
-			<div>
+            Текущее значение: {value} <br />
-				<h2>Store</h2>
+            Предыдущее значение: {prevValueRef.current}
-				<input type='text	' placeholder='Search...' onChange={handleChange} />
+        </div>
-			</div>
+    )
 			<div>
 				<FaRegUser size={24} color='#3258e3' />
 				<button>Profile</button>
 			</div>
 		</header>
 	)
 }
-function Product() {
+function ScrollList() {
-    const handlerMouseEnter = event => {
+    const listRef = useRef(null);
-        const img = event.target;
+    
-        img.style.border = '5px solid yellow';
+    const scrollToBottom = () => {
        if(listRef.current) {
            listRef.current.scrollTop = listRef.current.scrollHeight;
        }
    }
-    const handlerMouseOut = event => {
+        
-        const img = event.target;
+    return (
-        img.style.border = '';
+        <>
-        console.log(event);
+            <div ref={listRef} 
-    }
+               style={{height: 200, overflowY: 'auto', border: '1px solid black'}}>
-	return (
+                {[...Array(20)].map((_,i)=>(
-		<div className={styles.product}>
+                    <div key={i}>Элемент № {i + 1}</div>
-			<img src={SneakersImage} alt='' onMouseEnter={handlerMouseEnter} onMouseOut={handlerMouseOut} />
+                ))}
-			<div className={styles.content}>
+            </div>
-				<div className={styles.title}>
+            <button onClick={scrollToBottom}>Прокрутить вниз</button>
-					<h4>Sneakers Red & White 2025</h4>
+        </>
-					<button onClick={() => handleClick(0)} onMouseEnter={handlerMouseEnter} onMouseOut={handlerMouseOut}>+</button>
+    )
 				</div>
 				<p className={styles.description}>NIKE</p>
 				<p className={styles.price}>$38.00</p>
 			</div>
 		</div>
 	)
 }
-
+        
 function App() {
 	return (
 		<>
-			<div className={styles.container}>
+			<h1>Hello, React!</h1>
-			<Header />
+            <ScrollList />
 				<ul className={styles.list}>
 					<li>
 						<Product />
 					</li>
 					<li>
 						<Product />
 					</li>
 					<li>
 						<Product />
 					</li>
 				</ul>
 			</div>
 		</>
 	)
 }
@@ -1,123 +0,0 @@
@use './assets/styles/variables' as *;
 .header {
 	display: flex;
 	justify-content: space-between;
 	align-items: center;
 	padding: 20px;
 	background-color: white;
 	border-bottom-left-radius: 10px;
 	border-bottom-right-radius: 10px;
 	div {
 		&:first-child {
 			display: flex;
 			align-items: center;
 			gap: 20px;
 			h2 {
 				color: $primary-color;
 			}
 			input {
 				border-radius: 5px;
 				outline: none;
 				font-size: 16px;
 				border: 1px solid gainsboro;
 				padding: 5px 10px;
 				&:focus {
 					border: 1px solid $primary-color;
 				}
 			}
 		}
 		&:last-child {
 			display: flex;
 			align-items: center;
 			gap: 10px;
 			button {
 				outline: 0;
 				border: 0;
 				border-radius: 5px;
 				padding: 5px 15px;
 				font-size: 16px;
 				background-color: $primary-color;
 				color: $white-color;
 				font-weight: 600;
 				cursor: pointer;
 				&:hover {
 					background-color: $seconday-color;
 				}
 			}
 		}
 	}
 }
 .container {
 	max-width: 1220px;
 	margin: 0 auto;
 }
 .list {
 	display: flex;
 	justify-content: space-between;
 	border-radius: 10px;
 	margin-top: 100px; /* временно */
 	padding: 20px;
 	background-color: white;
 	list-style: none;
 }
 .product {
 	display: flex;
 	flex-direction: column;
 	width: 350px;
 	gap: 20px;
 	border-radius: 10px;
 }
 .content {
 	display: flex;
 	flex-direction: column;
 	gap: 10px;
 }
 .title {
 	display: flex;
 	justify-content: space-between;
 	align-items: center;
 	h4 {
 		font-size: 18px;
 	}
 	button {
 		background-color: black;
 		color: white;
 		border: 0;
 		border-radius: 50%;
 		outline: 0;
 		font-size: 20px;
 		padding: 5px 10px;
 		cursor: pointer;
 	}
 }
 img {
 	border-radius: 10px;
 }
 .description {
 	color: gray;
 }
 .price {
 	font-weight: bold;
 }
@@ -1,9 +1,8 @@
 import { StrictMode } from 'react'
 import { createRoot } from 'react-dom/client'
 // удаляем import './index.css'
 import App from './App.jsx'
 createRoot(document.getElementById('root')).render(
 	<StrictMode>
 		<App />
 	</StrictMode>
 )