passing-notes-sse

A middleware for sending and receiving server-sent events.

Usage

Install passing-notes-sse by running:

yarn add passing-notes-sse

This library provides a middleware that takes requests and responses with header:

Content-Type: text/event-stream

It serializes/deserializes between raw text event streams and async iterators (or ReadableStreams) of event objects like so:

import {setTimeout} from 'node:timers/promises'
import {compose} from 'passing-notes'
import * as sse from 'passing-notes-sse'

export default compose(
  sse.serialize,
  () => (request) => ({
    status: 200,
    headers: {
      'Content-Type': 'text/event-stream'
    },
    body: new ReadableStream({
      async pull(controller) {
        await setTimeout(1000)
        controller.enqueue({ data: 'Hello World!' })
      }
    })
  })
)

import {compose, sendRequest as sendRequestBase} from 'passing-notes'
import deserializeSse from 'passing-notes-sse'

const sendRequest = compose(
  sse.deserialize,
  () => sendRequest
)

const response = await sendRequest({
  method: 'GET',
  url: 'http://localhost:8080'
})

for await (const event of stream) {
  console.log(event)
  // { data: 'Hello World!' }
}