Hono Server Sent Events

let sseConnections = new Set<any>();

app.get("/sse", async (c) => {
  return streamSSE(c, async (stream) => {
    sseConnections.add(stream);

    stream.onAbort(() => {
      sseConnections.delete(stream);
    });

    // keep connection alive
    while (true) {
      await stream.writeSSE({
        event: "ping",
        data: "pong",
        retry: 5000,
      });
      await stream.sleep(30000);
    }
  });
});

app.get("/sse/send", async (c) => {
  for (const connection of sseConnections) {
    await connection.writeSSE({
      data: "It is " + new Date().toISOString(),
      event: "time-update",
    });
  }

  return c.text("ok");
});