JSFiddle - React, Tailwind, and code Playground

HTML

<script>
    function check_entireform(theform) {
        alert('Form submission prevented!');
        
        alert('Now submitting form manually!');
        theform.submit();
    }
</script>

<form method="post" action="./new.php" onsubmit="check_entireform(this); return false;">
<input type="submit" name="email" id="jemail"/>
</form>