Simple SSE Server in Node (taken from somewhere online!)

sse.js

var PORT = 8081;

var http = require("http");
var fs = require("fs");
var url = require("url");

http.createServer(function (request, response) {
  var parsedURL = url.parse(request.url, true);
  var pathname = parsedURL.pathname;
  if (pathname === "/admin/push") {

    response.writeHead(200, {
      "Content-Type": "text/event-stream",
      "Cache-Control": "no-cache",
      "Access-Control-Allow-Origin": "*"
    });

    response.write(":" + Array(2049).join(" ") + "\n"); // 2kB padding for IE
    response.write("retry: 2000\n");

    var lastEventId = Number(request.headers["last-event-id"]) || Number(parsedURL.query.lastEventId) || 0;

    var timeoutId = 0;
    var i = lastEventId;
    var c = i + 100;
    var f = function () {
      if (++i < c) {
        response.write("id: " + i + "\n");
        var data = {
          Topic: 'checkout', 
          EventName: 'view_cart', 
            Payload: {
            cart_token: "65a190e348777cfb326d59eeaf44a56d"
            }
        };

        response.write("data: " + JSON.stringify(data) + "\n\n");
        timeoutId = setTimeout(f, 1000);
      } else {
        response.end();
      }
    };

    f();

    response.on("close", function () {
      clearTimeout(timeoutId);
    });

  } else {
    if (pathname === "/") {
      pathname = "/index.html";
    }
    if (pathname === "/index.html" || pathname === "../eventsource.js") {
      response.writeHead(200, {
        "Content-Type": pathname === "/index.html" ? "text/html" : "text/javascript"
      });
      response.write(fs.readFileSync(__dirname + pathname));
    }
    response.end();
  }
}).listen(PORT);