Class StatefulSubject<Actions, State>

Example

// The State will be the type of data you want to manipulate.
interface State {
  authors: string[]
}

// The Actions are a record of "action name" to a parameter.
// If the action doesn't require a parameter, use `void`.
type Actions = {
  'add author': string
  'action that doesnt need a parameter': void
}

// To get the best out of this API, pass the Actions type and State
// during construction.
const subject = new StatefulSubject<Actions, State>(
  {
    __INIT__: () => ({ authors: [] }),

    'add author': (state, author) => state.authors.includes(author) ? state : {
       ...state,
       authors: [...state.authors, author],
    },

    'action that doesnt need a parameter': (state) => state
  }
)

subject.fork().pipeTo(write(console.info))
// { action: '__INIT__', state: { authors: [] } }

subject.dispatch('add author', 'Jane Austin')
// { action: 'add author', param: 'Jane Austin', state: { authors: ['Jane Austin'] } }

subject.dispatch('add author', 'Jane Austin')
// **Nothing will be queued as the state did not change.**
Copy