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Commit e6cb57d

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create undoable counter
Signed-off-by: Amit Amrutiya <amitamrutiya2210@gmail.com>
1 parent a9a3351 commit e6cb57d

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‎React/undoable-counter/README.md‎

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# Undoable Counter
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![image](https://github.com/user-attachments/assets/342c93d9-b2ab-404b-8ec8-28bb144aa3b2)

‎React/undoable-counter/package.json‎

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{
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"name": "faq-comp",
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"version": "0.1.0",
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"private": true,
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"dependencies": {
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"@testing-library/jest-dom": "^5.17.0",
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"@testing-library/react": "^13.4.0",
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"@testing-library/user-event": "^13.5.0",
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"react": "^18.2.0",
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"react-dom": "^18.2.0",
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"react-scripts": "5.0.1",
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"web-vitals": "^2.1.4"
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},
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"scripts": {
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"start": "react-scripts start",
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"build": "react-scripts build",
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"test": "react-scripts test",
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"eject": "react-scripts eject"
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},
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"eslintConfig": {
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"extends": [
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"react-app",
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"react-app/jest"
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]
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},
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"browserslist": {
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"production": [
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">0.2%",
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"not dead",
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"not op_mini all"
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],
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"development": [
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"last 1 chrome version",
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"last 1 firefox version",
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"last 1 safari version"
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]
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}
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}
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="utf-8" />
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<link rel="icon" href="%PUBLIC_URL%/favicon.ico" />
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<meta name="viewport" content="width=device-width, initial-scale=1" />
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<meta name="theme-color" content="#000000" />
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<meta
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name="description"
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content="Web site created using create-react-app"
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/>
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<link rel="apple-touch-icon" href="%PUBLIC_URL%/logo192.png" />
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<!--
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manifest.json provides metadata used when your web app is installed on a
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user's mobile device or desktop. See https://developers.google.com/web/fundamentals/web-app-manifest/
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-->
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<link rel="manifest" href="%PUBLIC_URL%/manifest.json" />
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<!--
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Notice the use of %PUBLIC_URL% in the tags above.
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It will be replaced with the URL of the `public` folder during the build.
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Only files inside the `public` folder can be referenced from the HTML.
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Unlike "/favicon.ico" or "favicon.ico", "%PUBLIC_URL%/favicon.ico" will
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work correctly both with client-side routing and a non-root public URL.
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Learn how to configure a non-root public URL by running `npm run build`.
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-->
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<title>React App</title>
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</head>
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<body>
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<noscript>You need to enable JavaScript to run this app.</noscript>
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<div id="root"></div>
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<!--
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This HTML file is a template.
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If you open it directly in the browser, you will see an empty page.
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You can add webfonts, meta tags, or analytics to this file.
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The build step will place the bundled scripts into the <body> tag.
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To begin the development, run `npm start` or `yarn start`.
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To create a production bundle, use `npm run build` or `yarn build`.
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-->
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</body>
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</html>

‎React/undoable-counter/src/App.js‎

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import { useState } from "react";
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function App() {
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const [value, setValue] = useState(0);
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const [redoList, setRedoList] = useState([]);
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const [history, setHistory] = useState([]);
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const [undoCount, setUndoCount] = useState(0);
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const maintainHistory = (key, prev, curr) => {
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console.log(key, prev, curr);
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const obj = {
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action: key,
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prev,
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curr,
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};
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const copyHistory = [...history];
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copyHistory.unshift(obj); //
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setHistory(copyHistory);
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};
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const handleClick = (key) => {
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const val = parseInt(key);
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console.log(key);
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maintainHistory(key, value, val + value);
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setValue((existingValue) => existingValue + val);
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};
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const handleUndo = () => {
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//stack LIFO
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//histor [ +10, +1] redolist [-1]
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if (history.length) {
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if (undoCount + 1 > 5) {
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alert("You cant undo beyond limit=5");
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return;
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}
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setUndoCount((prev) => prev + 1);
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const copyHist = [...history];
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const firstItem = copyHist.shift();
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setHistory(copyHist);
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setValue(firstItem.prev);
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const copyRedoList = [...redoList];
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copyRedoList.push(firstItem);
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setRedoList(copyRedoList);
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}
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};
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console.log(redoList);
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const handleRedo = () => {
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if (redoList.length) {
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const copyRedoList = [...redoList];
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const poppedValue = copyRedoList.pop();
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setRedoList(copyRedoList);
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const { action, prev, curr } = poppedValue;
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setValue(curr);
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maintainHistory(action, prev, curr);
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// [+100,+10,+1]
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}
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};
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return (
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<div className="App">
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<h1>Undoable Counter</h1>
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<div className="action-btn">
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<button onClick={handleUndo}>Undo</button>
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<button onClick={handleRedo}>Redo</button>
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</div>
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<div className="user-actions">
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{[-100, -10, -1].map((btn) => {
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return <button onClick={() => handleClick(btn)}>{btn}</button>;
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})}
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<div style={{ fontSize: 40 }}>{value}</div>
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{["+1", "+10", "+100"].map((btn) => {
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return <button onClick={() => handleClick(btn)}>{btn}</button>;
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})}
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</div>
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<div className="history">
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{history.map((item) => {
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return (
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<div className="row">
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<div>{item.action}</div>
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<div>{`[ ${item.prev} -> ${item.curr} ]`}</div>
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</div>
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);
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})}
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</div>
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</div>
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);
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}
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export default App;

‎React/undoable-counter/src/index.css‎

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body {
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margin: 0;
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font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
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'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
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sans-serif;
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-webkit-font-smoothing: antialiased;
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-moz-osx-font-smoothing: grayscale;
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}
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code {
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font-family: source-code-pro, Menlo, Monaco, Consolas, 'Courier New',
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monospace;
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}
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.App {
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text-align: center;
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}
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.user-actions{
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display: flex;
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justify-content: center;
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align-items: center;
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}
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button{
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width: 100px;
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height: 40px;
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border: none;
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outline: none;
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font-size: 20px;
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border-radius: 5px;
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color: #fff;
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background-color: purple;
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margin: 10px;
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font-weight: bold;
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cursor: pointer;
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}
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.history{
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width: 300px;
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height: 300px;
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margin: 100px auto;
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border: 1px solid black;
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overflow-y: auto;
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}
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.row{
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display: flex;
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justify-content: space-around;
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align-items: center;
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padding: 5px;
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font-size: 20px;
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}

‎React/undoable-counter/src/index.js‎

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import React from 'react';
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import ReactDOM from 'react-dom/client';
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import './index.css';
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import App from './App';
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const root = ReactDOM.createRoot(document.getElementById('root'));
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root.render(
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<React.StrictMode>
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<App />
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</React.StrictMode>
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);

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