Compute keys that are different between two JS objects

getChangedProperties.js

/**
 * @param {Object} oldData
 * @param {Object} newData
 * @returns {Array.<string>} A list of key names that are different between
 * oldData and newData.
 */
export const getChangedProperties = (oldData, newData) =>
  Object.keys(oldData).reduce(
    (acc, key) => (oldData[key] !== newData[key] ? [...acc, key] : acc),
    []
  );