form.html

<!DOCTYPE html>
<html>
    <head>
        <title>Write URL on which you want to go</title>
        <script>
            
            function foo(){
                console.log("foo called");
                var form = document.getElementById("myform");
                var url = document.getElementById("url").value;
                console.log(url);
                form.action = url;
                console.log(form.action);
                form.submit();
            }
        </script>
    </head>
    <body>
        <form method="POST" id="myform">
            Enter url with transfer protocol in below text box<br>
            e.g.
            url: https://www.wikipedia.org/<br>    
            url:
            <input type="text" id="url">
            <input type="button" name="btnSubmit" value="GO!" onclick="foo()">
        </form>
    </body>
</html>