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AFSM

Types

State

export type State = string | MiddleState

The FSM’s state. Stable states are strings (e.g. 'idle', FSM.INIT); intermediate states are MiddleState instances.

state.toString() always returns a string form:

  • String state: returns itself
  • MiddleState: returns ${action}ing

IFSM

export interface IFSM extends FSM {}

A self-referential interface for FSM, mainly used in decorator type signatures (to avoid circular references). In everyday use, just extends FSM.

ChangeOption

The config object for @ChangeState.

export interface ChangeOption {
  ignoreError?: boolean
  action?: string
  success?: (result: any) => any
  fail?: (err: FSMError) => any
  context?: ((this: IFSM, ...args: any[]) => string | object) | string | object
  abortAction?: string
  sync?: boolean
}

ignoreError?: boolean

Don’t throw on failure — return the error as the value instead.

  • Async mode: Promise.resolve(err)
  • Sync mode: return err

Defaults to false.

action?: string

Custom action name. Defaults to the decorated method’s name. Intermediate state name = action + 'ing'.

success?: (result: any) => any

Success callback. this refers to the instance owning the decorated method. Receives the original method’s return value.

fail?: (err: FSMError) => any

Failure callback. this refers to the instance. Receives the FSMError.

context?: string | object | ((this, ...args) => string | object)

Composition mode: delegate the state change to another FSM associated with context (via FSM.get(context)).

  • String: FSM.get('timer')
  • Object: FSM.get(obj) (uses WeakMap)
  • Function: this.context.call(this, ...args) returns a string or object

See Composing FSMs.

abortAction?: string

If currently in a MiddleState whose action equals abortAction, calling this method invokes middle.abort(fsm).

See Abort & Interruption.

sync?: boolean

Sync mode. See Sync Mode.

  • true: sync return values are returned directly (not wrapped in Promise); errors are thrown, not rejected
  • false (default): always returns a Promise

FSMEventTypes

interface FSMEventTypes {
  stateChanged: [State, State, any]
}

Parameter types for the stateChanged event: [newState, oldState, err?]. Extend with custom event types via the FSM<MyEvents> generic.

See also