This package provides an easy API for making Event Source requests with all the features of Fetch API, and supports browsers and Node.js.

For Node.js, v18.0.0 or higher required.

npm install fetch-sse

import { fetchEventData } from 'fetch-sse';

await fetchEventData('/api/sse', {
  method: 'POST',
  data: { foo: 'bar' },
  headers: {
    'Content-Type': 'application/json',
    'Authorization': 'Bearer token'
  },
  onMessage: (event) => {
    console.log(event);
  }
})

You can pass in other parameters in a similar way to the Fetch API.

import { fetchEventData } from 'fetch-sse';

await fetchEventData('/api/sse', {
  method: 'POST',
  data: { foo: 'bar' },
  headers: {
    'Content-Type': 'application/json',
    'Authorization': 'Bearer token'
  },
  signal: ctrl.signal,
  onMessage: (event) => {
    console.log(event.data);
  }
})

Interface

export interface IFetchOptions {
  method?: string;
  headers?: HeadersInit | Record<string, any>;
  data?: Record<string, any>;
  signal?: AbortSignal;
  onMessage?: (event: ServerSentEvent | null, done?: boolean) => void;
  onOpen?: (res?: Response) => void;
  onClose?: () => void;
  onError?: (error: any) => void;
}

// decoded event
export interface ServerSentEvent {
  event: string | null;
  data: string;
  raw: string[];
}

The event stream is a simple stream of text data that encoded using UTF-8. You can find more information here.

• Data-only messages

raw:

data: {"username": "bobby", "time": "02:33:48"}\n\n

parsed:

{
  event: null,
  data: '{"username": "bobby", "time": "02:33:48"}',
  raw: [
    'data: {"username": "bobby", "time": "02:33:48"}'
  ]
}

• Named events

raw:

:HTTP\n
id: 1\n
event: result\n
data: {"username": "bobby", "time": "02:33:48"}\n\n

parsed:

{
  event: 'result',
  data: {"username": "bobby", "time": "02:33:48"},
  raw: [
    ':HTTP',
    'id: 1',
    'event: result',
    'data: {"username": "bobby", "time": "02:33:48"}'
  ]
}

this package is written in typescript and compatible with browsers and nodejs, You might need to polyfill TextDecoder for old versions of browsers.