React Js Check if Array or Object contains Value

<!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">
        const { useState } = React;

function App() {
            const [demoArray, setDemoArray] = useState([]);

return (
                <div class='component'>
                    <h3>React Js Check Element Exist in Array</h3>
                    {demoArray.length === 0 ? (
                        <p>Array is empty</p>
                    ) : (
                        demoArray.map((item) => <p key={item}>{item}</p>)
                    )}
                </div>
            );
        }
        ReactDOM.render(<App />, document.getElementById("app"));
    </script>
    <style>
        .component {
            padding: 20px;
            border: 1px solid #ccc;
        }

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

p {
            font-size: 16px;
            margin-bottom: 5px;
        }
    </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">
        const { useState } = React;
​
        function App() {
            const [demoArray, setDemoArray] = useState([]);
​
            return (
                <div class='component'>
                    <h3>React Js Check Element Exist in Array</h3>
                    {demoArray.length === 0 ? (
                        <p>Array is empty</p>
                    ) : (
                        demoArray.map((item) => <p key={item}>{item}</p>)
                    )}
                </div>
            );
        }
        ReactDOM.render(<App />, document.getElementById("app"));
    </script>
    <style>
        .component {
            padding: 20px;
            border: 1px solid #ccc;
        }
​
        h3 {
            font-size: 24px;
            margin-bottom: 10px;
        }
​
        p {
            font-size: 16px;
            margin-bottom: 5px;
        }
    </style>
</body>
​
</html>