Did you try the below steps in JavaScript?

1. Parse the querystring and create hidden field for each name/value p
+air by 
   document.write("<input type=hidden name="+ name + " value ="+ value
+>");

2. Make the form method to POST
    document.form.method="POST";

3. Specify the form action 
   document.form.action="http://127.0.0.1/cgi-bin/test.cgi";

4. Do the form submit
     document.form.submit();
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