WebSocket vs Polling connection

Source: https://www.youtube.com/watch?v=IVhwW1JkULo&t=749s

WebSockets are used in real-time connections when the frontend and backend are constantly exchanging data in both directions, such as when a real-time system requires consistent communication back and forth.

If you utilize a serverless stack, setting up websockets will be difficult since serverless apps do not have a long enough lifespan to send responses and maintain the server connection alive. Serverless is short-lived; you generate it and then kill it.

Polling can be used when we simply want a one-time response.

Example: polling

const FIVE_MINUTS = 5 * 60 * 1000;
const url = "https://example.com/api/v1/book";
const delay = (ms: number) => new Promise((res) => setTimeout(res, ms));

setLoading(true);
const startDate = Date.now();

while (true) {
  if (Date.now() - startDate > FIVE_MINUTS) {
    alert("Time out");
    setLoading(false);
    return;
  }
  const delayPromise = delay(500);
  try {
    const res = await fetch(url);
    if (res.status === 404) {
      await delayPromise;
      continue;
    }
    if (!res.ok) {
      throw new Error(`Http request failed with status: ${res.status}`);
    }
    const data = await res.json();
    console.log("data", data);
  } catch (err) {
    console.error(err);
  } finally {
    setLoading(false);
    return;
  }
  await delayPromise;
}