JSFiddle - React, Tailwind, and code Playground

HTML

<html>
    
    <head>
        <script>
            function upload() {
            console.log('ok')
                alert("I am an alert box!");
            }
        </script>
    </head>
    
    <body>
        <form enctype="multipart/form-data" method="post" onsubmit="return upload();">
            <input type="file" name="file">
            <input type="submit" name="upload2" value="Datei hochladen">
        </form>
    </body>

</html>