import { useState, useEffect, useRef } from "react";
import ReactDOM from "react-dom/client";
function App() {
const [inputValue, setInputValue] = useState("");
const previousInputValue = useRef("");
useEffect(() => {
previousInputValue.current = inputValue;
}, [inputValue]);
return (
<>
<input
type="text"
value={inputValue}
onChange={(e) => setInputValue(e.target.value)}
/>
<h2>Current Value: {inputValue}</h2>
<h2>Previous Value: {previousInputValue.current}</h2>
</>
);
}
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<App />);
/*
Start typing in the input field and you will
see the current- and previous value.
*/
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport"
content="width=device-width, initial-scale=1" />
<title>React App</title>
</head>
<body>
<div id="root"></div>
</body>
</html>