My problem is the JavaScript Error NaN. Everything works perfectly in my LocalHost (file: ///), but as soon as I upload it, it says "NaN" everywhere. I don't understand what could be the cause, this is my first project with JavaScript.

I left out a lot of the HTML code, but that is also explained in the JavaScript.

HTML:

<div class="coinsdisplay">
    <input id="coins" type="text" disabled name="" value="0" class="coinInput">
</div>
<div class="cps">
    <p id="cps">0 Coins/s</p>
</div>

<script src="public/js/main.js"></script>

<script>
  window.onload= loadGame();
</script>

JS:

var coincount = 0;
var autoClick = 0;
var computer = 0;
var multiplier = 1;

// Single Click
function addCoin() {
  coincount = coincount + 1
  update()
}

// Updater
function update() {
  document.getElementById('coins').value = coincount;
  document.getElementById('cps').innerHTML = (((autoClick) + (computer*2))*multiplier) + " Coins/s";
  //AutoClicker
  document.getElementById('amountAutoClick').innerHTML = autoClick;
  document.getElementById('cosAutoClick').innerHTML = ((autoClick+1) * 12) + " Coins";
  //Computer
  document.getElementById('amountComputer').innerHTML = computer;
  document.getElementById('cosComputer').innerHTML = ((computer+1) * 15) + " Coins";
}

function timer() {
  coincount = coincount + autoClick;
  coincount = coincount + computer*2;
  update()
}
setInterval(timer, 1000)

// AutoClicker
function buyAutoClick() {
  if (coincount >= ((autoClick+1) * 12)) {
      coincount = coincount - ((autoClick+1) * 12);
      autoClick = autoClick + 1;
      update()
  }
}

// Computer
function buyComputer() {
  if (coincount >= ((computer+1) * 100)) {
      coincount = coincount - ((computer+1) * 50);
      computer = computer + 1;
      update()
  }
}

// SaveGame
function saveGame() {
  localStorage.setItem("coincount", coincount);
  localStorage.setItem("autoClick", autoClick);
  localStorage.setItem("computer", computer);
}
setInterval(saveGame, 1000)

function loadGame() {
  coincount = localStorage.getItem("coincount");
  coincount = parseInt(coincount);
  autoClick = localStorage.getItem("autoClick");
  autoClick = parseInt(autoClick);
  computer = localStorage.getItem("computer");
  computer = parseInt(computer);
  update()
}

I hope someone can help me, I wish you all a nice day.