some code to try mobx-state-tree

m.coffee

types = require('mobx-state-tree').types

M1 = types
.model
  a: types.string
  b: types.frozen
  c: types.map(types.number)
.actions (self) ->
  changeA: (x) -> self.a = x
  changeB: (y) -> self.b = y
  changeC: (x) -> self.c.set 'a2', x

m1 = M1.create a: "demo", b: ['a','b', ['c', 'd']], c: {a: 1}

console.log m1.c.get('a')

m1.changeC(33)

console.log m1.c.toJSON()