Verifica periodicamente o resultado de uma promessa

check.promise.js

let check = (cb, timeout = 30000, step = 5000) => {
  if (0 >= timeout) {
    return Promise.reject("TIMEOUT");
  }
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log("Checking...", timeout);
      cb().then(found => {
				console.log("Checked!", found);
        if (found) {
          return resolve();
        }
        return check(cb, timeout - step, step).then(resolve, reject);
      }, reject);
    }, step);
  });
};