HTMLify

const container = document.querySelector(".container");
const seats = document.querySelectorAll(".row .seat:not(.occupied)");
const count = document.getElementById("count");
const total = document.getElementById("total");
const movieSelect = document.getElementById("movie");
let ticketPrice = +movieSelect.value;

function populateUI() {
  const selectedSeats = JSON.parse(localStorage.getItem("selectedSeats"));
  if (selectedSeats !== null && selectedSeats.length > 0) {
    seats.forEach((seat, index) => {
      if (selectedSeats.indexOf(index) > -1) seat.classList.add("selected");
    });
  }
  const selectedMovieIndex = localStorage.getItem("selectedMovieIndex");
  if (selectedMovieIndex !== null)
    movieSelect.selectedIndex = selectedMovieIndex;
}

function setMovieData(movieIndex, moviePrice) {
  localStorage.setItem("selectedMovieIndex", movieIndex);
  localStorage.setItem("selectedMoviePrice", moviePrice);
}

function updateSelectedCount() {
  const selectedSeats = document.querySelectorAll(".row .seat.selected");
  const seatsIndex = [...selectedSeats].map((seat) => [...seats].indexOf(seat));
  localStorage.setItem("selectedSeats", JSON.stringify(seatsIndex));
  const selectedSeatsCount = selectedSeats.length;
  count.innerText = selectedSeatsCount;
  total.innerText = selectedSeatsCount * ticketPrice;
}

movieSelect.addEventListener("change", (e) => {
  ticketPrice = +e.target.value;
  setMovieData(e.target.selectedIndex, e.target.value);
  updateSelectedCount();
});

container.addEventListener("click", (e) => {
  if (
    e.target.classList.contains("seat") &&
    !e.target.classList.contains("occupied")
  ) {
    e.target.classList.toggle("selected");
    updateSelectedCount();
  }
});

// Init
populateUI();
updateSelectedCount();