кориг. домашно (2-ра зад.)

function solve() {

  const url = `https://judgetests.firebaseio.com/schedule/`;  //имаше интервал в края!
  let lastId = 'depot';
  //let lastStop = "";
  let infoField = document.querySelector('#info span');
  let departButton = document.getElementById('depart');
  let arriveButton = document.getElementById('arrive');

  function depart() {

    let currUrl = `${url}${lastId}.json`;
    fetch(currUrl)
      .then(response => response.json())
      .then(response => infoField.textContent = `Next stop ${response.name}`)
      //lastStop = response.name; //не е нужно
      //lastId = response.next;
      //)
      .catch(() => {
        infoField.textContent = 'Error';
        departButton.disabled = true;
        arriveButton.disabled = true;
      });

    departButton.disabled = true;
    arriveButton.disabled = false;
  }

  function arrive() {

    fetch(`${url}${lastId}.json`)
      .then(response => response.json())
      .then(result => {
        infoField.textContent = `Arriving at ${result.name}`;
        lastId = result.next; //Тук вече трябва да се запази
      })
      .catch(() => {
        infoField.textContent = 'Error';
        departButton.disabled = true;
        arriveButton.disabled = true;
      });

    //infoField.textContent = `Arriving at ${lastStop}`;
    arriveButton.disabled = true;
    departButton.disabled = false;
  }

  return {
    depart,
    arrive
  };
}

let result = solve();