setTimeout---5秒请求一次网络

let delay = 5000;

let timerId = setTimeout(function request() {
  ...发送请求...

  if (request failed due to server overload) {
    // 下一次执行的间隔是当前的 2 倍
    delay *= 2;
  }

  timerId = setTimeout(request, delay);

}, delay);

let timer = setTimeout(function func() {
  console.log(new Date());
  timer = setTimeout(func, 1000);
}, 1000);

setTimeout(() => {
  clearTimeout(timer);
}, 6000);