errMsg.js

var makeErrorHandler = function (msg) {
  //msg is the string passed via the call
  //the return anonyumous function is what is passed back to the callback of getData
  return function (error) {
    sendErrorToServer(error);
    showMessage(msg);
  };
};

getData(query, function (result) {
  //success
}, makeErrorHandler ('Could Not Get Data'));