How to use Select onchange to not show parameters in the url?

Question

I have the following select

<select onchange="location = options[selectedIndex].value" id="sel">
<option value="?cod=<%=cod%>&op=1">opção 1</option>
<option value="?cod=<%=cod%>&op=2">opção 2</option>
<option value="?cod=<%=cod%>&op=3">opção 3</option>
</select>

And the url appears: site/? Cod=x&op=1

I need select sent with internal processing

and the url stay = site/? Cod=x

can be with Hidden or js

Is it possible? thank you in advance for your responses

Answer 1

My suggestion is this: create a span shortly after the select (the span does not interfere with anything in the page layout, will be used only to receive a form from which will be sent the value of op). Will stay like this:

<select onchange="redir(this.value)" id="sel">
   <option value="?cod=11&op=1">opção 1</option>
   <option value="?cod=21&op=2">opção 2</option>
   <option value="?cod=31&op=3">opção 3</option>
</select>
<span id="tempform"></span>

Note that in the onchange a function will be called redir passing the value of option selected.

Now enter the function on the page:

function redir(i){
   // pega o valor do select e separa em grupos cod=X e op=X
   var params = i.match(/\?(.+)&(.+)/);
   // pega cod=X
   var cod = "?"+params[1];
   // pega apenas a parte numérica de op=X
   var op = params[2].match(/\d+/)[0];

   // monta o formulário para ser enviado com o valor de op
   // note que o formulário não aparecerá na página com display: none
   var form = '<form style="display: none;" method="post" action="'+location.href+cod+'">'
   +'<input name="op" value="'+op+'">'
   +'</form>';

   // insere o formulário no span
   document.getElementById("tempform").innerHTML = form;
   // faz o submit do formulário
   document.querySelector("#tempform form").submit();
}

By firing the onchange of select, the page will be redirected to itself in this way:

pagina.asp?cod=valor_no_option

At the same time the form created by the script with the field will be submitted op via POST.

This way you can recover the values cod and op in ASP with:

<%
cod = request("cod")
op = request("op")
%>