Class WithEvents<V>

A state machine that fires events when state changes.

const transitions = StateMachine.fromList(`a`, `b`, `c`);
const m = new StateMachineWithEvents(transitions);
m.addEventListener(`change`, event => {
 console.log(`${event.priorState} -> ${event.newState}`);
});
m.addEventListener(`stop`, event => {
 console.log(`State machine has reached final state`);
});

Type Parameters

VextendsTransitions

Hierarchy (View Summary)

SimpleEventEmitter<StateMachineEventMap<V>>
- WithEvents

Index

Constructors

constructor

new WithEvents<V extends Transitions>(
m: V,
opts?: StateMachineWithEventsOpts<V>,
): Flow.StateMachine.WithEvents<V>
Create a state machine with initial state, description and options
Type Parameters
- VextendsTransitions
Parameters
- m: V
  Machine description
- opts: StateMachineWithEventsOpts<V> = {}
  Options for machine (defaults to {debug:false})
Returns Flow.StateMachine.WithEvents<V>
Overrides SimpleEventEmitter.constructor

Accessors

changedAt

get changedAt(): number
Returns timestamp when state was last changed. See also elapsed

Returns number

elapsed

get elapsed(): number
Returns milliseconds elapsed since last state change. See also changedAt

Returns number

isDisposed

get isDisposed(): boolean
Returns boolean
Inherited from SimpleEventEmitter.isDisposed

isDone

get isDone(): boolean
Returns true if state machine is in its final state

Returns boolean

state

get state(): string
Returns string
set state(newState: StateNames<V>): void
Gets or sets state. Throws an error if an invalid transition is attempted. Use isValid() to check validity without changing.

If newState is the same as current state, the request is ignored silently.
Parameters
- newState: StateNames<V>
Returns void

statesDefined

get statesDefined(): readonly StateNames<V>[]
Return a list of all defined states

Returns readonly StateNames<V>[]

statesPossible

get statesPossible(): readonly (null | StateNames<V>)[]
Return a list of possible states from current state.

If list is empty, no states are possible. Otherwise lists possible states, including 'null' for terminal

Returns readonly (null | StateNames<V>)[]

Methods

addEventListener

addEventListener<K extends keyof StateMachineEventMap<V>>(
    name: K,
    listener: (
        event: StateMachineEventMap<V>[K],
        sender: SimpleEventEmitter<StateMachineEventMap<V>>,
    ) => void,
): void
Adds event listener.
Type Parameters
- Kextendskeyof StateMachineEventMap<V>
  Events
Parameters
- name: K
  Event name
- listener: (
  event: StateMachineEventMap<V>[K],
  sender: SimpleEventEmitter<StateMachineEventMap<V>>,
  ) => void
  Event handler
Returns void
Throws
Error if emitter is disposed

Inherited from SimpleEventEmitter.addEventListener

dispose

dispose(): void
Returns void
Inherited from SimpleEventEmitter.dispose

`Protected`fireEvent

fireEvent<K extends keyof StateMachineEventMap<V>>(
type: K,
args: StateMachineEventMap<V>[K],
): void
Fire event
Type Parameters
- Kextendskeyof StateMachineEventMap<V>
Parameters
- type: K
  Type of event
- args: StateMachineEventMap<V>[K]
  Arguments for event
Returns void
Inherited from SimpleEventEmitter.fireEvent

isValid

isValid(newState: StateNames<V>): boolean
Returns true if newState is valid transition from current state. Use validateTransition if you want an explanation for the false results.
Parameters
- newState: StateNames<V>
Returns boolean

next(): null | string
Moves to the next state if possible. If multiple states are possible, it will use the first. If machine is finalised, no error is thrown and null is returned.

Returns null | string
Returns new state, or null if machine is finalised

removeEventListener

removeEventListener<K extends keyof StateMachineEventMap<V>>(
    type: K,
    listener: (
        event: StateMachineEventMap<V>[K],
        sender: SimpleEventEmitter<StateMachineEventMap<V>>,
    ) => void,
): void
Remove event listener
Type Parameters
- Kextendskeyof StateMachineEventMap<V>
Parameters
- type: K
- listener: (
  event: StateMachineEventMap<V>[K],
  sender: SimpleEventEmitter<StateMachineEventMap<V>>,
  ) => void
Returns void
Inherited from SimpleEventEmitter.removeEventListener

reset

reset(): void
Resets machine to initial state

Returns void

validateTransition

validateTransition(newState: StateNames<V>): void
Throws if it's not valid to transition to newState
Parameters
- newState: StateNames<V>
Returns void

Class WithEvents<V>

Type Parameters

Hierarchy (View Summary)

Index

Constructors

Accessors

Methods

Constructors

constructor

Type Parameters

Parameters

Returns Flow.StateMachine.WithEvents<V>

Accessors

changedAt

Returns number

elapsed

Returns number

isDisposed

Returns boolean

isDone

Returns boolean

state

Returns string

Parameters

Returns void

statesDefined

Returns readonly StateNames<V>[]

statesPossible

Returns readonly (null | StateNames<V>)[]

Methods

addEventListener

Type Parameters

Parameters

Returns void

Throws

dispose

Returns void

ProtectedfireEvent

Type Parameters

Parameters

Returns void

isValid

Parameters

Returns boolean

next

Returns null | string

removeEventListener

Type Parameters

Parameters

Returns void

reset

Returns void

validateTransition

Parameters

Returns void

Settings

On This Page

`Protected`fireEvent