Mobx: toJS make set obj to array

[joey-lucky]

Intended outcome:
toJS make set to array

Actual outcome:
expect set obj

How to reproduce the issue:

let mobx = require("mobx");
let a = mobx.observable(new Set());
console.log(mobx.toJS(a)); // []  expect Set {}

Versions
Mobx：4.15.7

[FredyC]

Just to note here if turns out to be a bug (I am not sure), you will need to upgrade to MobX 6, we no longer support previous versions.

[FredyC]

Actually, it's working correctly in V6, so if need this, you have to upgrade ;)

https://codesandbox.io/s/heuristic-fire-z2szs?file=/src/index.js

[mweststrate]

Note that in v4 / v5 it is possible to set exportMapsAsObjects option, that achieves the same (despite the name also works for sets). https://github.com/mobxjs/mobx/blob/mobx4and5/docs/refguide/tojson.md