Why declare const inside for loop?

Mark Wood's answer is correct, but I'll try to provide a little more detail. Frank, you are correct that the array is getting reset with each iteration of the loop, but keep in mind that there are 2 loops, and this is happening in the outer loop. The inner loop is filling up the array, and then the filled array is added to the spaces array via the push() method. At that point, we iterate into the outer loop, which resets the array. We aren't concerned about losing the contents of the array, as we no longer need the values because they're safely tucked away in the spaces array. When we've gone through all the columns and all the rows, the spaces array gets returned.

With each iteration of the 'x' loop, a new column array is created, which is then pushed to the spaces array. The final spaces array that's returned will have 7 column arrays inside it.