chrome-extension-removed-part-2

app.get = function (url, headers, data) {
  var xhr = new XMLHttpRequest();
  var deferred = Promise.defer();
  xhr.onreadystatechange = function () {
    if (xhr.readyState === 4) {
      if (xhr.status >= 400 || xhr.status < 200) {
        var e = new Error(xhr.statusText);
        e.status = xhr.status;
        deferred.reject(e);
      } else deferred.resolve(xhr.responseText);
    }
  };
  xhr.open(data ? "POST" : "GET", url, true);
  for (var id in headers) xhr.setRequestHeader(id, headers[id]);
  if (data) {
    var arr = [];
    for (e in data) arr.push(e + '=' + data[e]);
    data = arr.join('&');
  }
  xhr.send(data ? data : '');
  return deferred.promise;
};