Go to your main site, and look at the code of the search form in the object inspector (right-click on the form - the "show code" item - find the form tag in the DOM tree in the inspector).
- In the
form tag you will see the action attribute with the path to the correct search route. For example, before /search/node - In the
input tag inside the form, you will see the name attribute with the correct name of the search text field. For example, search_query
Now on your subdomain - just build the same form with the same field:
<form id="search" action="//site.com/search/node" method="get"> <input type="text" name="search_query"/> <input type="submit"/> </form>
Pay attention to the method="get" form - search forms usually send data to the server with a GET request, but perhaps in your case the form is sent using the POST method - look how it is done in the form on the main domain and do the same.
Also, the button can have type="submit" , or type="search" , also do it in the main form.
As a result, you will receive a working search form that takes you from the subdomain to the main domain, without javascript.