Send Form data with Cordova InAppBrowser

I'm trying to send a POST request to a PHP server using a form. The form is filled at runtime and stored inside a .js file. I can access the form by using $('#form') anytime.

My problem is here: I have to send this form using the Cordova InAppBrowser. I'm loading the page, but I'm not able to pass the form.submit() to the InAppBrowser page.

I'm using the following code:

javascript

var ref = window.open('https://www.paypal.com/it/cgi-bin/webscr', '_blank');
ref.addEventListener('loadstop', function (event) {
   ref.executeScript({
     file: "https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"
   }, 
   function () {
     ref.executeScript({
       code: "jQuery('#payform').submit();"
     });
   });
});
ref.show();

form

<form id="payform" action="https://www.paypal.com/it/cgi-bin/webscr" method="post" target="_self">;
<input type="hidden" ...
...
</form>

The page loads at the given url, but I'm not able to pass input elements. What am I doing wrong?

Thank you :)