Documentation / @eventkit/base / Stream

Class: Stream<T>

A Stream is a special type of AsyncObservable that allows values to be multicasted to many observers. Streams are like EventEmitters.

Every Stream is an AsyncObservable and can be used as a value producer. You can subscribe to a Stream, and you can call push to feed values to all observers.

Extends

• AsyncObservable<T>

Type Parameters

Type Parameter
T

Constructors

Constructor

new Stream<T>(init?): Stream<T>

Creates a new Stream instance.

Parameters

Parameter	Type
init?	StreamInit<T>

Returns

Stream<T>

Overrides

AsyncObservable<T>.constructor

Accessors

closed

Get Signature

get closed(): boolean

Returns true if this stream has been closed and is no longer accepting new values.

Returns

boolean

---

observed

Get Signature

get observed(): boolean

Returns true if this stream has any active observers.

Returns

boolean

---

subscribers

Get Signature

get subscribers(): Subscriber<T>[]

Returns

Subscriber<T>[]

Inherited from

AsyncObservable.subscribers

Methods

asObservable()

asObservable(): AsyncObservable<T>

Creates a new AsyncObservable with this Stream as the source. You can do this to create custom observer-side logic of the Stream and conceal it from code that uses the AsyncObservable.

Returns

AsyncObservable<T>

AsyncObservable that this Stream casts to

---

cancel()

cancel(): Promise<void>

Signals completion to all observers and closes the stream.

Returns

Promise<void>

Overrides

AsyncObservable.cancel

---

drain()

drain(): Promise<void>

Returns a promise that resolves when all the work scheduled against the observable has completed (i.e. subscriber callbacks or cleanup handlers).

Returns

Promise<void>

Inherited from

AsyncObservable.drain

---

finally()

finally(onfinally?): Promise<any>

Schedules a cleanup action that gets executed when the observable is disposed of. Optionally, a callback can be provided to inform the behavior of the created action.

Parameters

Parameter	Type	Description
onfinally?	null | () => void	Optional callback to execute after completion or error

Returns

Promise<any>

A promise that resolves when the action has completed

Inherited from

AsyncObservable.finally

---

push()

push(value): void

Feeds a new value to all observers of this stream.

Parameters

Parameter	Type	Description
value	T	The value to emit to all observers

Returns

void

---

subscribe()

subscribe(callback?): Subscriber<T>

Registers and returns a new Subscriber that will call the provided callback for each value emitted by the Stream. The callback will be passed the value emitted to the Stream as an argument.

While this method is similar to AsyncObservable's subscribe method, the key difference is that the generator that is passed to the Subscriber is a unique implementation that emulates the desired behavior of the Stream.

You can still use the returned Subscriber object like a Promise which can be awaited to wait for the Stream to be closed.

Parameters

Parameter	Type
callback?	SubscriberCallback<T>

Returns

Subscriber<T>

Overrides

AsyncObservable.subscribe