docs: function (url, json, cb) {
      var req;
  
      if (window.ActiveXObject)
        req = new ActiveXObject('Microsoft.XMLHTTP');
      else if (window.XMLHttpRequest)
        req = new XMLHttpRequest();
      else
        throw "Strider: No ajax"
  
      req.onreadystatechange = function () {
        if (req.readyState==4)
          cb(req.responseText);
      };
      var data;
      if(window.CircularJSON) {
        data = window.CircularJSON.stringify(json);
      } else {
        data = JSON.stringify(json);
      }
      req.open("POST", url, true);
      req.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
      req.setRequestHeader('X-Browser-String', BrowserStack.browser_string);
      req.setRequestHeader('X-Worker-UUID', BrowserStack.worker_uuid);
      req.setRequestHeader('Content-type', 'application/json');
      req.send(data);
    }