one alternative is to post to server via XMLHttpRequest

ajax post for extension

// POST the data to the server using XMLHttpRequest (AJAX)
function ajaxpost(data)
{
    var req = new XMLHttpRequest();
    req.open("POST", "http://compraymudate.com/admin/apipost/", true);

    var params = "title=" + document.getElementById("title").value + 
                 "&content=" + document.getElementById("content").value + 
                 "&price=" + document.getElementById("price").value +
                 "&rooms=" + document.getElementById("rooms").value +
                 "&baths=" + document.getElementById("baths").value +
                 "&pueblo=" + document.getElementById("pueblo").value +
                 "&mainimage=" + document.getElementById("mainimage").value;

    req.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    req.setRequestHeader("Content-length", params.length);
    req.setRequestHeader("Connection", "close");

    req.send(params);

    req.onreadystatechange = function() 
    { 
        // If the request completed, close the extension popup
        if (req.readyState == 4)
            var test = req.responseText;
            alert(test);
    };

    return false;
}