createViewModel with array

I’m trying to use createViewModel to make a viewModel of an object with an array. When I edit the array property of the viewModel, the changes are immediately reflected on the original object. Not sure if this is a bug or if I’m using this wrong. Help would be much appreciated!

import { observable } from "mobx";
import { createViewModel } from "mobx-utils";

class AppState {
  @observable user = {
    arr: [1]
  };
}

const appState = new AppState();
const userState = createViewModel(appState.user);

console.log(appState.user.arr[0]);  // 1
console.log(userState.arr[0]);  // 1

userState.arr[0] = 5;

// User.arr[0] should still be 1
console.log(appState.user.arr[0]);  // 5
console.log(userState.arr[0]);  // 5

https://codesandbox.io/s/minimal-mobx-react-project-6hthy

[danielkcz]

Sorry, I am not familiar with this particular utility. By reading docs, it indeed should behave the way you are saying. Probably best if someone else who knows about it can have a look.

ping @ItamarShDev (you did some changes to it a while ago)

[danielkcz]

And when would expect the value change would happen? MobX is not asynchronous, it does the change right away. What would be even use case where you need to see old values after changing it? 😃