Button Function

<!DOCTYPE html>

<html>

    <head>

    <title>Javascript testing</title>

    </head>

    <body>

    <p id="demo">This paragraph will change after clicking that button below!</p>

    <button type="button" onclick="randomFunction()">Click!</button>

    <script>

    function randomFunction() {
        document.getElementById("demo").innerHTML = "Paragraph changed!";

    }
    </script>

    </body>

</html>