Hyperapp: Change `update` to `getState`

[xialvjun]

In thunks, we do not know the current state because maybe some other actions has changed the state during the thunk. So you offered an update function.

But a better solution is offer a getState function...

[jorgebucaran]

@xialvjun The update function can _take a function that receives the latest state_. I find this scheme an improvement to ReduxThunk getState.

update(state => ({ count: state.count + 1 }))

And for completeness, when you don't need the latest state to calculate the next state, just pass the new state/slice to update.

update({ count: 1 })

Does that make things clear?

[xialvjun]

But if the state has been changed during the thunk, then state.count is wrong.

[jorgebucaran]

@xialvjun That problem is solved using:

update(state => ({ count: state.count + 1 }))

The state passed to the inner thunk above is always up-to-date.

[jorgebucaran]

@xialvjun In other words:

const actions = {
  upAsyncNaive(state) { // Hey! state may be out-of-sync here!
    return update => update({ count: state.count + 1 }) 
  },
  upAsyncSmart(state) { // No problem here!
    return update => update(state => ({ count: state.count + 1 }))
  }
}

[xialvjun]

got it. thanks very much.

[jorgebucaran]

Glad you figured it out! 🎉