React Js Set Focus on Input field after rendering

<!DOCTYPE html>
<html>

<body>
    <div id="app"></div>
    <script type="text/babel">
        function App() {
            const { useRef, useEffect } = React;
            const inputRef = useRef(null);

useEffect(() => {
                inputRef.current.focus();
            }, []);

return (
                <div className='container'>
                    <h3>React Js set focus on input field after Rendering</h3>
                    <input ref={inputRef} type="text" />
                </div>
            );

}

ReactDOM.render(<App />, document.getElementById("app"));
    </script>
    <style>
        .container {
            margin: 0 auto;
            width: 500px;
            text-align: center;
            box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.12), 0 2px 4px 0 rgba(0, 0, 0, 0.24);
            padding: 20px;
        }

.container h3 {
            font-size: 20px;
            margin-bottom: 10px;
        }

.container input {
            padding: 10px;
            border: 1px solid #ccc;
            border-radius: 5px;
            font-size: 16px;
            width: 300px;
            outline: none;
        }

.container input:focus {
            border-color: #007bff;
        }
    </style>
</body>

</html>

 
<!DOCTYPE html>
<html>
​
<head>
    <meta charset="UTF-8" />
    <script src="https://unpkg.com/react@17.0.2/umd/react.development.js"></script>
    <script src="https://unpkg.com/react-dom@17.0.2/umd/react-dom.development.js"></script>
    <script src="https://unpkg.com/@babel/standalone@7.14.7/babel.min.js"></script>
</head>
​
<body>
    <div id="app"></div>
    <script type="text/babel">
        function App() {
            const { useRef, useEffect } = React;
            const inputRef = useRef(null);
​
            useEffect(() => {
                inputRef.current.focus();
            }, []);
​
            return (
                <div className='container'>
                    <h3>React Js set focus on input field after Rendering</h3>
                    <input ref={inputRef} type="text" />
                </div>
            );
​
        }
​
        ReactDOM.render(<App />, document.getElementById("app"));
    </script>
    <style>
        .container {
            margin: 0 auto;
            width: 500px;
            text-align: center;
            box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.12), 0 2px 4px 0 rgba(0, 0, 0, 0.24);
            padding: 20px;
        }
​
        .container h3 {
            font-size: 20px;
            margin-bottom: 10px;
        }
​
        .container input {
            padding: 10px;
            border: 1px solid #ccc;
            border-radius: 5px;
            font-size: 16px;
            width: 300px;
            outline: none;
        }
​
        .container input:focus {
            border-color: #007bff;
        }
    </style>
</body>
​
</html>