server-events-nodejs

A library for setting up server-sent events in Node.js. This library was inspired by work done by Dino Paskvan on express-sse

Install

npm

npm install server-events-nodejs --save

yarn

yarn add server-events-nodejs

Usage

const { Source, EventStream } = require('server-events-nodejs');

const express = require('express');
const cuid = require('cuid');
const port = "8080";

const source = new Source(cuid);
const app = express();

app.listen(port, () => {
  console.log('Server ready!');
});

app.use(
  EventStream.init(source, { 
    no_ids: false, // if you need id: key/value (from the cuid lib) as part of the text-stream response - set to 'true'
    pad_for_ie: false, // if the HTTP request is from an IE 8/9 browser - set to 'true'
    prefered_event_name: 'update', // if you need event: key/value (here set to 'update')  as part of the text-stream resposne - set here to whatever you like
    prefer_event_name: true // enforce the prefered event name to be used in the text-stream response
  })
);

app.get('/notifications', function(req){
    console.log('headers: ', req.headers);

    // send comment: '!this is a comment!'
    // send with event name: 'update'
    // send with retry: 4500 (4.5 seconds)
    source.send({
            ids: [ '123', '456' ],
            timestamp: Date.now()
      }, 
      '!this is a comment!', // comment
      'update', // event
      4500 // retry
    );
    
});

Then, you need to setup the front-end accordingly

const evtSource = new EventSource('http://localhost:8080/notifications');

evtSource.addEventListener('open', function(e) {
  console.log("connection is open!");
}, false);

evtSource.addEventListener('error', function(e) {
  console.error(e);
  evtSource.close();
})

evtSource.addEventListener('update', function(e) {
  console.log("message: ", JSON.parse(e.data));
}, false);

/* - logs to console -

  connection is open!

  message: {
    "ids": [
      "123",
      "456"
    ],
    "timestamp": 1608970168797
  }
  
*/

License

MIT