HTMLify

var character = document.getElementById("character");
var game = document.getElementById("game");
var interval;
var both = 0;
var counter = 0;
var currentBlocks = [];

function moveLeft() {
  // to move the ball left
  var left = parseInt(
    window.getComputedStyle(character).getPropertyValue("left")
  );
  if (left > 0) {
    character.style.left = left - 2 + "px";
  }
}
function moveRight() {
  // to move the ball right
  var left = parseInt(
    window.getComputedStyle(character).getPropertyValue("left")
  );
  if (left < 380) {
    character.style.left = left + 2 + "px";
  }
}
document.addEventListener("keydown", event => {
  if (both == 0) {
    both++;
    if (event.key === "ArrowLeft") {
      interval = setInterval(moveLeft, 1);
    }
    if (event.key === "ArrowRight") {
      interval = setInterval(moveRight, 1);
    }
  }
});
document.addEventListener("keyup", event => {
  clearInterval(interval);
  both = 0;
});

var blocks = setInterval(function () {
  var blockLast = document.getElementById("block" + (counter - 1));
  var holeLast = document.getElementById("hole" + (counter - 1));
  if (counter > 0) {
    var blockLastTop = parseInt(
      window.getComputedStyle(blockLast).getPropertyValue("top")
    );
    var holeLastTop = parseInt(
      window.getComputedStyle(holeLast).getPropertyValue("top")
    );
  }
  if (blockLastTop < 400 || counter == 0) {
    var block = document.createElement("div");
    var hole = document.createElement("div");
    block.setAttribute("class", "block");
    hole.setAttribute("class", "hole");
    block.setAttribute("id", "block" + counter);
    hole.setAttribute("id", "hole" + counter);
    block.style.top = blockLastTop + 100 + "px";
    hole.style.top = holeLastTop + 100 + "px";
    var random = Math.floor(Math.random() * 360);
    hole.style.left = random + "px";
    game.appendChild(block);
    game.appendChild(hole);
    currentBlocks.push(counter);
    counter++;
  }
  var characterTop = parseInt(
    window.getComputedStyle(character).getPropertyValue("top")
  );
  var characterLeft = parseInt(
    window.getComputedStyle(character).getPropertyValue("left")
  );
  var drop = 0;
  if (characterTop <= 0) {
    alert("Game over. Score: " + (counter - 9));
    clearInterval(blocks);
    location.reload();
  }
  for (var i = 0; i < currentBlocks.length; i++) {
    let current = currentBlocks[i];
    let iblock = document.getElementById("block" + current);
    let ihole = document.getElementById("hole" + current);
    let iblockTop = parseFloat(
      window.getComputedStyle(iblock).getPropertyValue("top")
    );
    let iholeLeft = parseFloat(
      window.getComputedStyle(ihole).getPropertyValue("left")
    );
    iblock.style.top = iblockTop - 0.5 + "px";
    ihole.style.top = iblockTop - 0.5 + "px";
    if (iblockTop < -20) {
      currentBlocks.shift();
      iblock.remove();
      ihole.remove();
    }
    if (iblockTop - 20 < characterTop && iblockTop > characterTop) {
      drop++;
      if (iholeLeft <= characterLeft && iholeLeft + 20 >= characterLeft) {
        drop = 0;
      }
    }
  }
  if (drop == 0) {
    if (characterTop < 480) {
      character.style.top = characterTop + 2 + "px";
    }
  } else {
    character.style.top = characterTop - 0.5 + "px";
  }
}, 1);