Documentation / @eventkit/http / EventSource

Class: EventSource

A drop-in replacement for the standard EventSource class that provides an Observable interface for handling Server-Sent Events (SSE). This class extends the native EventSource class and adds the ability to consume events as an AsyncObservable using the asObservable method.

Example

import { EventSource } from "@eventkit/http";

const source = new EventSource("https://api.example.com/events");

// Get raw message data
source.asObservable<string>().subscribe(data => {
  console.log("Received:", data);
  // { id: undefined, type: "message", data: "hello" }
});

// Get full event objects including metadata
source.asObservable<string>({ dematerialize: true }).subscribe(event => {
  switch (event.type) {
    case "message":
      console.log("Message:", event.data.data);
      break;
    case "error":
      console.error("Error:", event.data);
      break;
    case "open":
      console.log("Connection opened");
      break;
  }
});

See

MDN Reference

Extends

• EventSource

Constructors

Constructor

new EventSource(url, init?): EventSourceObservable

Parameters

Parameter	Type
url	string | URL
init?	EventSourceInit

Returns

EventSourceObservable

Inherited from

EventSource.constructor

Properties

CLOSED

readonly CLOSED: 2;

Inherited from

EventSource.CLOSED

---

CONNECTING

readonly CONNECTING: 0;

Inherited from

EventSource.CONNECTING

---

onerror()

onerror: (this, ev) => any;

Parameters

Parameter	Type
this	EventSource
ev	ErrorEvent

Returns

any

Inherited from

EventSource.onerror

---

onmessage()

onmessage: (this, ev) => any;

Parameters

Parameter	Type
this	EventSource
ev	MessageEvent

Returns

any

Inherited from

EventSource.onmessage

---

onopen()

onopen: (this, ev) => any;

Parameters

Parameter	Type
this	EventSource
ev	Event

Returns

any

Inherited from

EventSource.onopen

---

OPEN

readonly OPEN: 1;

Inherited from

EventSource.OPEN

---

readyState

readonly readyState: 0 | 1 | 2;

Inherited from

EventSource.readyState

---

url

readonly url: string;

Inherited from

EventSource.url

---

withCredentials

readonly withCredentials: boolean;

Inherited from

EventSource.withCredentials

---

CLOSED

readonly static CLOSED: 2;

Inherited from

EventSource.CLOSED

---

CONNECTING

readonly static CONNECTING: 0;

Inherited from

EventSource.CONNECTING

---

OPEN

readonly static OPEN: 1;

Inherited from

EventSource.OPEN

Methods

addEventListener()

Call Signature

addEventListener<K>(
   type, 
   listener, 
   options?): void

Adds a new handler for the type event. Any given listener is added only once per type and per capture option value.

If the once option is true, the listener is removed after the next time a type event is dispatched.

The capture option is not used by Node.js in any functional way other than tracking registered event listeners per the EventTarget specification. Specifically, the capture option is used as part of the key when registering a listener. Any individual listener may be added once with capture = false, and once with capture = true.

Type Parameters

Type Parameter
K extends keyof EventSourceEventMap

Parameters

Parameter	Type
type	K
listener	(this, ev) => any
options?	boolean | AddEventListenerOptions

Returns

void

Inherited from

EventSource.addEventListener

Call Signature

addEventListener(
   type, 
   listener, 
   options?): void

Adds a new handler for the type event. Any given listener is added only once per type and per capture option value.

If the once option is true, the listener is removed after the next time a type event is dispatched.

The capture option is not used by Node.js in any functional way other than tracking registered event listeners per the EventTarget specification. Specifically, the capture option is used as part of the key when registering a listener. Any individual listener may be added once with capture = false, and once with capture = true.

Parameters

Parameter	Type
type	string
listener	EventListenerOrEventListenerObject
options?	boolean | AddEventListenerOptions

Returns

void

Inherited from

EventSource.addEventListener

---

asObservable()

Call Signature

asObservable<T>(opts): AsyncObservable<EventSourceEvent<T>>

Converts the EventSource into an AsyncObservable that yields either raw message data or full event objects depending on the options provided.

Type Parameters

Type Parameter	Description
T	The type of data contained in message events

Parameters

Parameter	Type	Description
opts	{ dematerialize: true; }	Configuration options for the observable
opts.dematerialize	true	When true, yields full event objects including metadata. When false or omitted, yields only the message data.

Returns

AsyncObservable<EventSourceEvent<T>>

An AsyncObservable that yields either raw message data or full event objects

Call Signature

asObservable<T>(opts?): AsyncObservable<EventSourceMessage<T>>

Converts the EventSource into an AsyncObservable that yields either raw message data or full event objects depending on the options provided.

Type Parameters

Type Parameter	Description
T	The type of data contained in message events

Parameters

Parameter	Type	Description
opts?	{ dematerialize: false; }	Configuration options for the observable
opts.dematerialize?	false	When true, yields full event objects including metadata. When false or omitted, yields only the message data.

Returns

AsyncObservable<EventSourceMessage<T>>

An AsyncObservable that yields either raw message data or full event objects

---

close()

close(): void

Returns

void

Inherited from

EventSource.close

---

dispatchEvent()

dispatchEvent(event): boolean

Dispatches a synthetic event event to target and returns true if either event's cancelable attribute value is false or its preventDefault() method was not invoked, and false otherwise.

Parameters

Parameter	Type
event	Event

Returns

boolean

Inherited from

EventSource.dispatchEvent

---

removeEventListener()

Call Signature

removeEventListener<K>(
   type, 
   listener, 
   options?): void

Removes the event listener in target's event listener list with the same type, callback, and options.

Type Parameters

Type Parameter
K extends keyof EventSourceEventMap

Parameters

Parameter	Type
type	K
listener	(this, ev) => any
options?	boolean | EventListenerOptions

Returns

void

Inherited from

EventSource.removeEventListener

Call Signature

removeEventListener(
   type, 
   listener, 
   options?): void

Removes the event listener in target's event listener list with the same type, callback, and options.

Parameters

Parameter	Type
type	string
listener	EventListenerOrEventListenerObject
options?	boolean | EventListenerOptions

Returns

void

Inherited from

EventSource.removeEventListener