sse.js

index.js

const cors = require('cors')
const express = require('express')
const bodyParser = require('body-parser')

const app = express()

let clients = []

const addSubscribe = (req, res) => {
  res.writeHead(200, { Connection: 'keep-alive', 'Content-Type': 'text/event-stream' })

  const id = Date.now()

  clients.push({ id, res })

  console.log(`Client connected: ${id}`)

  req.on('close', () => {
    console.log(id)
    clients = clients.filter((client) => client.id !== id)
  })
}

const addMessage = (req, res) => {
  const msg = req.body

  res.json(msg)
  clients.forEach((client) => client.res.write(`data: ${JSON.stringify(msg)}\n\n`))
}

app.use(cors())
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({ extended: false }))

app.post('/message', addMessage)
app.get('/subscribe', addSubscribe)
app.get('/status', (_, res) => res.json(clients.length))

app.listen(3000, () => console.log(`App listening on port ${3000}`))