code: function load(path, callback, errorCallback) {
    try {
      var xhr = new XMLHttpRequest();
      xhr.open("GET", path, true);
      xhr.onreadystatechange = function() {
        if (xhr.readyState === 4) {
          if (xhr.status === 200 || xhr.status === 304) {
            try {
              var response = JSON.parse(xhr.responseText);
              callback(response);
            } catch (e) {
              errorCallback(e);
            }
          } else {
            errorCallback(xhr);
          }
        }
      };
      xhr.setRequestHeader("Content-Type", "application/json");
      xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
      xhr.send();
    } catch (e) {
      errorCallback(e);
    }
  }
docs: Vanilla Ajax data transfer
  @param {String} path
  @param {Function} callback
  @param {Function} errorCallback