Events endpoint working example

server/events.ts

@@ -0,0 +1,32 @@
+import type { Express } from "express";
+
+export function setUpEvents(app: Express): void {
+  // https://stackoverflow.com/a/59041709
+  app.get("/events", (_req, res) => {
+    res.setHeader("Cache-Control", "no-cache");
+    res.setHeader("Content-Type", "text/event-stream");
+    res.setHeader("Access-Control-Allow-Origin", "*");
+    res.setHeader("Connection", "keep-alive");
+
+    // https://stackoverflow.com/a/69938612
+    // Without this Express compression prevents any messages from being
+    // sent until `res.end()` is called
+    res.setHeader("Cache-Control", "no-cache, no-transform");
+
+    res.flushHeaders();
+
+    let counter = 0;
+    let interValID = setInterval(() => {
+      counter++;
+      console.log("write", counter);
+      res.write(`data: ${JSON.stringify({ num: counter })}\n\n`); // res.write() instead of res.send()
+    }, 1000);
+
+    // If client closes connection, stop sending events
+    res.on("close", () => {
+      console.log("client dropped me");
+      clearInterval(interValID);
+      res.end();
+    });
+  });
+}

server/index.ts

@@ -8,6 +8,7 @@ import morgan from "morgan";
 import path from "path";
 import { LoggedInUser } from "~/validators/user";
 import { setUpAuth } from "./auth";
+import { setUpEvents } from "./events";
 import { setUpMockAuth } from "./mock-auth";
 import { setUpSeed } from "./seed";
 
@@ -15,6 +16,7 @@ const MODE = process.env.NODE_ENV;
 const BUILD_DIR = path.join(process.cwd(), "server/build");
 
 const app = express();
+app.disable("x-powered-by");
 app.use(compression());
 
 // You may want to be more aggressive with this caching
@@ -31,6 +33,7 @@ try {
   setUpAuth(app);
   setUpMockAuth(app, mockUserFromHTTPCall);
   setUpSeed(app);
+  setUpEvents(app);
 } catch (err) {
   console.error(err);
 }