/*eslint-disable brace-style*/
function createXMLHttpRequest() {
  try {
    return new XMLHttpRequest();
  }
  catch(e) {}
  try {
    return new ActiveXObject('Msxml2.XMLHTTP');
  }
  catch (e) {}
  try {
    return new ActiveXObject('Microsoft.XMLHTTP');
  }
  catch (e) {}
}
/*eslint-enable brace-style*/

function getURLSync(url) {
  var request = createXMLHttpRequest();
  request.open('GET', url, /*asynchronous?*/false);
  return request.responseText;
}

function postDataToURL(data, url, callback) {
  if (!callback) {
    callback = postDataToURL.defaultCallback;
  }
  var request = createXMLHttpRequest();
  if (!request) {
    return callback(Error('XMLHttpRequest is unsupported'));
  }
  postDataToURL.running = (postDataToURL.running || 0) + 1;
  request.onreadystatechange = function() {
    if (request.readyState !== 4) {
      return;
    }
    request.onreadystatechange = null;
    postDataToURL.running = (postDataToURL.running || 0) - 1;
    callback(request.status === 200 ? null : request.status, request.responseText);
  };
  request.open('POST', url);
  request.setRequestHeader('Content-Type', 'application/json');
  request.send(JSON.stringify(data));
}

postDataToURL.defaultCallback = function(error) {
  // console.log('postDataToURL.defaultCallback', arguments)
};