EventSource is a WHATWG-conformant implementation of the\nserver-sent events interface. It opens a persistent HTTP connection to a\nserver that responds with the text/event-stream content type and dispatches\nthe events it receives without closing the connection.
import { EventSource } from 'undici'\n\nconst eventSource = new EventSource('http://localhost:3000')\neventSource.onmessage = (event) => {\n console.log(event.data)\n}\nConstructing an EventSource for the first time emits a one-time\nExperimentalWarning with the code 'UNDICI-ES'. The interface is also\ninstalled onto globalThis as globalThis.EventSource.
<EventTarget>The EventSource interface receives server-sent events over an HTTP\nconnection. Instances are created with the new EventSource()\nconstructor and emit 'open', 'message', and\n'error' events.
\n\nStability: 1 - Experimental
\n
Creates a new EventSource and immediately begins connecting to url. The\nrequest is sent with the Accept: text/event-stream header, a cache mode of\nno-store, and an initiator type of other.
If url cannot be parsed, a SyntaxError DOMException is thrown.
import { EventSource } from 'undici'\n\nconst eventSource = new EventSource('http://localhost:3000', {\n withCredentials: true\n})\nimport { EventSource, Agent } from 'undici'\n\nclass CustomHeaderAgent extends Agent {\n dispatch (opts) {\n opts.headers['x-custom-header'] = 'hello world'\n return super.dispatch(...arguments)\n }\n}\n\nconst eventSource = new EventSource('http://localhost:3000', {\n node: {\n dispatcher: new CustomHeaderAgent()\n }\n})\nCloses the connection, if any, aborts the underlying request, and sets\neventSource.readyState to CLOSED. Once closed, the\nEventSource does not attempt to reconnect. Calling close() on an already\nclosed EventSource has no effect.
A read-only number representing the state of the connection. It is one of the\nfollowing constants:
\nEventSource.CONNECTING (0) — the connection has\nnot yet been established, or it was closed and is being re-established.EventSource.OPEN (1) — the connection is open and\nevents are being dispatched as they are received.EventSource.CLOSED (2) — the connection is not open\nand is not being re-established.A read-only string providing the URL of the event stream, after resolution\nagainst the environment's base URL.
" }, { "textRaw": "Type: {boolean}", "name": "withCredentials", "type": "boolean", "meta": { "added": [ "v6.5.0" ], "changes": [] }, "stability": 1, "stabilityText": "Experimental", "desc": "A read-only boolean indicating whether the EventSource was instantiated with\nCORS credentials (true), or not (false, the default). It reflects the\nwithCredentials option passed to the constructor.
An event handler that is invoked when an 'open' event is\ndispatched. Assigning a function registers it as the handler; assigning null\nremoves the current handler.
An event handler that is invoked when a 'message' event is\ndispatched. Assigning a function registers it as the handler; assigning null\nremoves the current handler.
An event handler that is invoked when an 'error' event is\ndispatched. Assigning a function registers it as the handler; assigning null\nremoves the current handler.
The numeric constant 0, representing the CONNECTING\nreadyState. It is defined as a read-only,\nnon-writable property on both the EventSource constructor and instances.
The numeric constant 1, representing the OPEN\nreadyState. It is defined as a read-only,\nnon-writable property on both the EventSource constructor and instances.
The numeric constant 2, representing the CLOSED\nreadyState. It is defined as a read-only,\nnon-writable property on both the EventSource constructor and instances.
Emitted when the connection is established and the\nreadyState becomes OPEN. The listener receives an\n<Event>.
import { EventSource } from 'undici'\n\nconst eventSource = new EventSource('http://localhost:3000')\neventSource.addEventListener('open', () => {\n console.log('connection opened')\n})\nEmitted when a message that has no explicit event field is received. The\nlistener receives a <MessageEvent> whose data, lastEventId, and origin\nproperties are populated from the server-sent event. Named events (those with an\nevent field) are dispatched under their own type and must be subscribed to with\naddEventListener().
import { createServer } from 'node:http'\nimport { EventSource } from 'undici'\n\nconst server = createServer((request, response) => {\n response.writeHead(200, {\n 'content-type': 'text/event-stream',\n 'cache-control': 'no-cache',\n connection: 'keep-alive'\n })\n\n response.write('event: ping\\n')\n response.write('data: connected\\n\\n')\n\n const interval = setInterval(() => {\n response.write(`data: ${Date.now()}\\n\\n`)\n }, 1000)\n\n request.on('close', () => clearInterval(interval))\n})\n\nserver.listen(3000, () => {\n const eventSource = new EventSource('http://localhost:3000')\n\n // Named event, delivered under its own type.\n eventSource.addEventListener('ping', (event) => {\n console.log('ping:', event.data)\n })\n\n // Unnamed event, delivered as 'message'.\n eventSource.onmessage = (event) => {\n console.log('message:', event.data)\n }\n})\nEmitted when the connection fails or is interrupted. The listener receives an\n<Event>. When the failure is recoverable, the EventSource transitions back to\nCONNECTING and retries after the reconnection time; when it is not, the\nEventSource transitions to CLOSED and does not reconnect.
import { EventSource } from 'undici'\n\nconst eventSource = new EventSource('http://localhost:3000')\neventSource.onerror = () => {\n if (eventSource.readyState === EventSource.CLOSED) {\n console.log('connection closed')\n } else {\n console.log('reconnecting')\n }\n}\n