blog | http server push with application/octet-stream

You create a normal express server.
one route to display the html
one route to stream data from the server. (push on custom event)

exemple to push event from the server

const express = require('express')
const app = express()

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

app.get('/stream', function (req, res) {
    res.writeHead(200, {
        'Content-Type': 'application/octet-stream'
    });
    var i = setInterval(() => res.write('salut'), 1000);
    setTimeout(() => {
        clearInterval(i);
        res.end();
    }, 5000)
})

app.listen(3000, function () {
    console.log('Example app listening on port 3000!')
})

exemple to read events from the browser

<!doctype html>
<html>
  <head>
    <title>Exemple</title>
  </head>
  <body>
    <p>Open console to see data</p>
  </body>
  <script>
      var xhr = new XMLHttpRequest(),
            method = 'GET',
            url = 'http://localhost:3000/stream';

        xhr.open(method, url, true);
        xhr.onprogress = function (event) {
            console.log(event.loaded + " / " + event.total);
        };

        xhr.seenBytes = 0;
        xhr.onreadystatechange = function () {
            console.log("state change.. state: " + xhr.readyState);
            if (xhr.readyState == 3) {
                var newData = xhr.response.substr(xhr.seenBytes);
                console.log("newData: " + newData + "");
                document.body.innerHTML += "New data: " + newData + "<br />";
                xhr.seenBytes = xhr.responseText.length;
                console.log("seenBytes: " + xhr.seenBytes);
            }
        };

        xhr.send();
  </script>
</html>