We need a function to compare two given arrays. The array is in one dimension only so we don't need any deep comparison. Put the following comparing function in the helpers.js file:

game.helper.arrayIsEqual = function(array1, array2) {
  if (array1.length !== array2.length) {
    return false;
  }
  for (var i = 0, len=array1.length; i < len; i++) {
    if (array1[i] !== array2[i]) {
      return false;
    }
  }
  return true;
};

Then we need another helper function that clears all the children nodes inside a given DOM element. Defining the following function inside the helpers.js file helps us to keep a cleaner code base:

game.helper.clearChildren = function(node) {
  while (node.lastChild) {
    node.removeChild(node.lastChild);
  }
};

We use three layers to...