In this tutorial, we'll create a Milliseconds Counter App using React and TypeScript. This project will demonstrate how to build a simple web application to display a continuously updating count of milliseconds since the app was loaded. We'll leverage the power of React's component-based architecture along with TypeScript's type safety to create a clean and maintainable codebase. Next, let's create a new TypeScript file named MillisecondsCounter.tsx in the src directory of your project. This file will contain the React component for our app: ``` const MilliSecondsCounter = () => { const ref = useRef<{ interval: NodeJS.Timeout }>({ interval: null }); const [milliseconds, setMilliseconds] = useState(0); const [started, setStarted] = useState(false); const [startedAt, setStartedAt] = useState(0); const start = () => { setStarted(true); setStartedAt(new Date().getTime()); }; const pause = () => { setStarted(false); }; useEffect(() => { if (!started) { clearInterval(ref.current.interval); return; } ref.current.interval = setInterval(() => { const elapsedTime = Date.now() - startedAt + milliseconds; setMilliseconds(elapsedTime); }, 1); return () => clearInterval(ref.current.interval); // eslint-disable-next-line react-hooks/exhaustive-deps }, [started]); return ( {new Date(milliseconds).toISOString().substr(11, 8)} MilliSeconds:{" "} {milliseconds} ``` In this tutorial, we've built a simple Milliseconds Counter App using React and TypeScript. We've leveraged the power of React's component-based architecture along with TypeScript's type safety to create a clean and maintainable codebase. This project serves as a great starting point for further exploration and experimentation with React and TypeScript web development. Happy coding!

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Milliseconds Counter App - Interview Question