express-sse

Easy Server-Sent Events for Express.js

What's this?

express-sse is a neat little package that makes working with Server-Sent Events (SSE) in Express.js a breeze. It gives you a simple pub/sub system for real-time, one-way communication from your server to clients. No more headaches setting up SSE endpoints or managing subscriptions!

Getting Started

First, grab the package:

npm install @dachendev/express-sse

How to Use

Quick Start

Here's the simplest way to get going:

const express = require('express')
const { expressSSE } = require('express-sse')

const app = express()
const { router, broker } = expressSSE(app)

router.sse('/events', (sse, req, res) => {
  sse.send('Hello, SSE!')
  sse.send({ message: 'I can send JSON too!', time: new Date() })
})

Real-world Scenario

Let's say you want to push updates to your clients:

const express = require('express')
const { expressSSE } = require('express-sse')

const app = express()
const { router, broker } = expressSSE(express.Router())

router.sse('/events', (sse, req, res) => {
  sse.comment('Waiting for updates...')
  sse.subscribe('updates', (data) => sse.send(data))
})

app.post('/update', (req, res) => {
  broker.publish('updates', { type: 'update', data: req.body })
  res.json({ success: true })
})

app.use(router)

Advanced Usage

Need more control? You can use the middlewares separately:

const express = require('express')
const { sseMiddleware, sseBrokerMiddleware, Broker } = require('express-sse')

const app = express()
const broker = new Broker()

app.get('/sse-only', sseMiddleware(), (req, res) => {
  req.sse.send('Using just the SSE middleware')
})

app.get(
  '/sse-with-broker',
  sseMiddleware(),
  sseBrokerMiddleware(broker),
  (req, res) => {
    req.sse.comment('Using both middlewares')
    req.sse.subscribe('updates', (data) => req.sse.send(data))
  }
)

app.post('/publish', (req, res) => {
  broker.publish('updates', req.body)
  res.json({ success: true })
})

API Quick Reference

• expressSSE(router, options): Sets up your router with SSE superpowers.
• router.sse(path, ...middlewares, handler): Creates an SSE endpoint.
• sse.send(data): Sends data (string or object) to the client.
• sse.comment(text): Sends a comment to the client (useful for keeping connections alive).
• sse.subscribe(topic, callback): Listens for updates on a topic.
• sse.unsubscribe(topic, id): Stops listening to a topic.
• sse.unsubscribeAll(): Unsubscribes from everything.
• broker.publish(topic, data): Broadcasts data to all subscribers of a topic.

That's it! Now go build some awesome real-time features with express-sse. If you run into any issues or have questions, feel free to open an issue on GitHub. Happy coding!