What is setTimeOut

setTimeOut waits for given ms before calling the callback function passed to it.

Executes a function or specified piece of code once the timer expires.

• for repeated execution, use setInterval.

Usage in polling

function poll(callback, interval, timeout) {
  let endTime = Date.now() + timeout;
  let checkCondition = function() {
    if (callback()) {
      // Success condition met
      return;
    } else if (Date.now() < endTime) {
      // Try again after interval
      setTimeout(checkCondition, interval);
    } else {
      // Timeout reached
      console.error('Polling timeout');
    }
  };
  checkCondition();
}

poll(
  () => {
    return fetch('/api/data')
      .then(res => res.json())
      .then(data => data.status === 'complete');
  },
  1000, // 1-second interval
  5000 // 5-second timeout
);