Deep transforms keys in Objects and Arrays

deepTransformKeys.js

// @flow

import { isObject, isArray, reduce, map } from 'lodash';

function deepTransformKeys<T>(transformKey: string => string, object: T): T {
  if (isObject(object)) {
    return reduce(
      object,
      (reduction, value, key) => {
        reduction[transformKey(key)] = deepTransformKeys(transformKey, value);
        return reduction;
      },
      {}
    );
  } else if (isArray(object)) {
    return map(object, value => deepTransformKeys(transformKey, value));
  } else {
    return object;
  }
}