better assign for redux reducers

assignAt.js

import {isString, assign, reduce, map, keys, isPlainObject, isNull} from 'lodash';

export const isKeyValue = function isKeyValue(h) {
	return isPlainObject(h) && !isNull(h)
};

export const assignAt = function assignAt(hash, path, newValue) {
	if (isKeyValue(path)) {
		return assign({}, hash,
				keys(path).reduce((memo, key) => assignAt(memo, key, path[key]), hash)
		);
	}

	isString(path) && (path = path.split('.'));

	const val = hash[path[0]];
	return assign({}, hash, {
		[path[0]]: (path.length === 1)
				? isKeyValue(val) && isKeyValue(newValue) ? assign({}, val, newValue) : newValue
				: assignAt(val, path.slice(1), newValue)
	});
};



import deepEqual from 'deep-equal';
console.log('[TESTS::assignAt]', {
	'extend middle key': deepEqual(
			assignAt(
					{a: {b: {c: 1}, d: 3}, f: {a: {b: 27}}, xx: 1},
					{
						'a.b': {hey: true},
						'f.a': {hello: false, b: 32}
					}
			),
			{a: {b: {c: 1, hey: true}, d: 3}, f: {a: {b: 32, hello: false}}, xx: 1}
	)
});