Just playing with how a native Array.prototype.mapKey would look.

Array.prototype.mapKey.js

/**
 *
 * @name: Array.prototype.mapKey
 * @author: @moekhalil (GitHub)
 *
 * @description: A prototype of a native Array.prototype.mapKey that
 *               would allow users to map over an array of objects
 *               and return the value of a specific key or nested key
 *
 * @param prop {string | string[]}
 * @returns {any[]}
 */

Array.prototype.mapKey = function (prop) {
  if (typeof prop === 'string') {
    return this.map((item) => item[prop]);
  }

  if (Array.isArray(prop)) {
    return this.map((item) =>
      prop.reduce((o, key) => item.hasOwnProperty(key) 
                                ? ({ ...o, [key]: item[key] }) 
                                : o
                  , {})
    );
  }

  if (typeof prop === 'undefined') {
    throw new Error(
      'mapKey requires a property name, array of property names, or function'
    );
  }
};