Documentation: es6 Map and Set in the state are not documented

[andruhon]

I did not find in the documentation how one should or should not use things like es6 Map and Set with Redux.

It seems like a new map should be created every time when we 'modify' it in the reducer, but I'm not sure that it is correct.

[gaearon]

I don’t think it’s a good idea to use them in Redux because they are optimized for mutability. If you want to have something efficient with similar semantics, consider using Immutable.js.

[andruhon]

Can this be mentioned somewhere in the docs, that it is not a good idea? (probably this issue is enough to be googled by keywords)

[mohammedabualsoud]

Yes, I'm not able to use ES6 map it seems it just deal with Objects, and array only.

[markerikson]

You can use Maps and Sets as state values, but it's not recommended due to serializability concerns. In addition, the built-in combineReducers utility expects to work with plain JS objects, so if you use a Map as part of your state tree, you would need to use other reducer handling instead of combineReducers.

[adrienjt]

FYI, I have implemented generic map and set reducers using plain JS objects in redux-data-structures:
https://github.com/adrienjt/redux-data-structures/blob/master/src/reducers/map.js
https://github.com/adrienjt/redux-data-structures/blob/master/src/reducers/set.js

[ChuckJonas]

Not sure if this is what @markerikson means by "serializability concerns", but for example if you try to do things like export/import your entire state with json, any maps in your reducer state will not properly be initialized. The basic issue is outlined here: http://2ality.com/2015/08/es6-map-json.html

[spedy]

@markerikson Maps are too "heavy" for me. Too much code needed to handle uniquenes and as you said serializability concerns... I am reflecting on the idea of using Sets to help maintain my states. In this example https://redux.js.org/usage/structuring-reducers/normalizing-state-shape allIds for example would be a Set.