express-sse.js

var path = require('path');
var express = require('express');

var app = express();
var openConnections = [];
 
global.emitEvent = function () {
    console.log("emit to clients " + openConnections.length);
    openConnections.forEach(function(res) {
        res.write('data: event' + "\n\n");
    });
}

// simple route to register the clients
app.get('/eventstream', function(req, res) {
 
    // set timeout as high as possible
    req.socket.setTimeout(0); // 0x7FFFFFFF

    res.writeHead(200, {
        'Content-Type': 'text/event-stream; charset=utf-8',
        'Cache-Control': 'no-cache',
        'Connection': 'keep-alive'
    });
    res.write('\n');
 
    // push this res object to our global variable
    openConnections.push(res);
 
    console.log("event stream new connection");

    req.on("close", function() {
        var toRemove;
        for (var j =0 ; j < openConnections.length ; j++) {
            if (openConnections[j] == res) {
                toRemove =j;
                break;
            }
        }
        openConnections.splice(j,1);
        console.log(openConnections.length);
    });
});

setInterval(function() {
  emitEvent();
}, 1000);

app.get('/', function(req, res) {
    res.sendfile(__dirname + '/index.html');
});

app.listen(3000);