How to catch an error in Tic Tac Toe?

Question

JavaScript

There is a code for the game "Tic-Tac-Toe"
https://codepen.io/ArtemVedischev/pen/oEzwOa?edito...
I wrote it myself, please do not scold too much. I am just learning.

In a single game, sometimes the check for empty fields fails, the computer makes a move to an already occupied field.
Checking for empty fields occurs in the getEmptySquare() function. And based on this, the field for the move is selected.
What's wrong?

Answer 1

And if so?

function getEmptySquare() { // почему get, если функция ничего не возвращает?
                                        // и почему square, если их там не один?
    emptySquare = []
    $('.item').each(function(){
      if (!this.textContent.length) {
        emptySquare.push(this.id)
      }
    })
    console.log('emptySquare:', emptySquare) 
}

In general, it’s cool for a start, but for good, more than half of it must be mercilessly thrown away, and the rest must be redone, and then added more.
A lot of duplication, strange names of variables and functions, their ambiguous behavior, and the logic let us down in places.