objectUtils.js

function reduceObject( obj, reduceCallback, initialValue ) {
    return Object.keys( obj ).reduce( function( acc, key, idx, arr ) {
        return reduceCallback( acc, obj[key], key, obj )
    }, initialValue )
}

var mapCollectionByProp = (list, fieldName) => list.reduce( (acc, v) => ({ ...acc, [v[fieldName]]: v }), {})

/**
 * returns new object with result of iterator() call for each property from keys
 * @param {Object} object
 * @param {Array} keys
 * @param {Function} iterator
 */

const updateObject = (object, keys, iterator = val => val) =>
  keys.reduce((acc, field) => ({ ...acc, [field]: iterator(object[field]) }), {...object})