Add an object key to a child object

withKeys.js

/**
 * Assigns object keys to the assigned child object
 * @returns {Object} keyed object
 */
const withKeys = (obj, uid = 'uid') => {
  return Object.keys(obj).reduce((keyObj, key) => {
    let keyed;
    if (typeof obj[key] === 'object') {
      keyed = {...obj[key], [uid]: key};
    } else {
      keyed = obj[key];
    }
    keyObj[key] = keyed;
    return keyObj;
  }, obj);
};