React Js Get First Element/item of Array

<!DOCTYPE html>
<html>

return (
                <div className='container'>
                    <h3>React Js Get first Element of array - using spread operator</h3>
                    <p>First Element of Array: {firstElement}</p>
                </div>
            );
        }

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

.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;
        }

p {
            font-size: 16px;
            color: green;
        }
    </style>
</body>

</html>