Phone Number Validation In React Js

<!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" data-presets="env,react">
        const { useState } = React;
        function App() {
            const [phoneNumber, setPhoneNumber] = useState("");
            const [errorMessage, setErrorMessage] = useState("");

const validatePhoneNumber = () => {
                const Regex = /^(?:(?:\+|0{0,2})91(\s*[\-]\s*)?|[0]?)?[6789]\d{9}$/;

if (phoneNumber === "") {
                    setErrorMessage("Phone Number field cannot be empty");
                } else if (!Regex.test(phoneNumber)) {
                    setErrorMessage("Invalid phone number");
                } else {
                    setErrorMessage("");
                }
            };

return (
                <div className='container'>
                    <h3>React Js Validate phone numbers (Indian Phone Number)</h3>

<input
                        type="text"
                        value={phoneNumber}
                        onChange={(e) => setPhoneNumber(e.target.value)}

/>
                    <button onClick={validatePhoneNumber}>Validate</button>
                    {phoneNumber && (
                        <pre>Phone Number Length {phoneNumber.length}</pre>
                    )}
                    {errorMessage && (
                        <pre style={{ color: "red" }}>{errorMessage}</pre>
                    )}

</div>
            );
        }

ReactDOM.render(<App />, document.getElementById("app"));
    </script>

h3 {
            font-size: 24px;
            margin-bottom: 10px;
        }

input[type="text"] {
            width: 100%;
            padding: 10px;
            font-size: 16px;
            border: 1px solid #ccc;
            border-radius: 4px;
            margin-bottom: 10px;
            box-sizing: border-box;
        }

pre {
            font-size: 14px;
            margin-top: 5px;
        }

pre[style] {
            color: red;
        }
    </style>
</body>

</html>