Implements the Observer interface and extends the Subscription class. While the Observer is the public API for consuming the values of an Observable, all Observers get converted to a Subscriber, in order to provide Subscription-like capabilities such as unsubscribe. Subscriber is a common type in RxJS, and crucial for implementing operators, but it is rarely used as a public API.

class Subscriber<T> extends Subscription implements Observer {
  static create<T>(next?: (x?: T) => void, error?: (e?: any) => void, complete?: () => void): Subscriber<T>
  constructor(destinationOrNext?: PartialObserver<any> | ((value: T) => void), error?: (e?: any) => void, complete?: () => void)
  protected isStopped: boolean
  protected destination: PartialObserver<any> | Subscriber<any>
  next(value?: T): void
  error(err?: any): void
  complete(): void
  unsubscribe(): void
  protected _next(value: T): void
  protected _error(err: any): void
  protected _complete(): void
  _unsubscribeAndRecycle(): Subscriber<T>

  // inherited from index/Subscription
  static EMPTY: Subscription
  constructor(unsubscribe?: () => void)
  closed: [object Object]
  unsubscribe(): void
  add(teardown: TeardownLogic): Subscription
  remove(subscription: Subscription): void
}

Static Methods

A static factory for a Subscriber, given a (potentially partial) definition of an Observer.

static create<T>(next?: (x?: T) => void, error?: (e?: any) => void, complete?: () => void): Subscriber<T>

Parameters

next	Optional. Default is undefined. The next callback of an Observer.
error	Optional. Default is undefined. The error callback of an Observer.
complete	Optional. Default is undefined. The complete callback of an Observer.

Returns

Subscriber<T>: A Subscriber wrapping the (partially defined) Observer represented by the given arguments.

Constructor

constructor(destinationOrNext?: PartialObserver<any> | ((value: T) => void), error?: (e?: any) => void, complete?: () => void)

Parameters

destinationOrNext	Optional. Default is undefined. A partially defined Observer or a next callback function.
error	Optional. Default is undefined. The error callback of an Observer.
complete	Optional. Default is undefined. The complete callback of an Observer.

Properties

Property	Type	Description
isStopped	boolean
destination	PartialObserver<any> | Subscriber<any>

Methods

next(value?: T): void

The Observer callback to receive notifications of type next from the Observable, with a value. The Observable may call this method 0 or more times.

Parameters

value

Optional. Default is undefined. The next value.

Returns

void:

error(err?: any): void

The Observer callback to receive notifications of type error from the Observable, with an attached Error. Notifies the Observer that the Observable has experienced an error condition.

Parameters

err	Optional. Default is undefined. The error exception.

Returns

void:

complete(): void

The Observer callback to receive a valueless notification of type complete from the Observable. Notifies the Observer that the Observable has finished sending push-based notifications.

Parameters

There are no parameters.

Returns

void:

unsubscribe(): void

Parameters

There are no parameters.

Returns

void

protected _next(value: T): void

Parameters

value

Type: T.

Returns

void

protected _error(err: any): void

Parameters

err	Type: any.

Returns

void

protected _complete(): void

Parameters

There are no parameters.

Returns

void

_unsubscribeAndRecycle(): Subscriber<T>

Parameters

There are no parameters.

Returns

Subscriber<T>