How to disable the creation of new numbers?

Question

JavaScript

I have numbers generated, and there is a check in the card for matches. When everything is filled horizontally and vertically, an alert pops up and after that everything should stop, but I continue to generate.
Code - https://codepen.io/anon/pen/JpORLP?editors=0010
Tell me how to fix it?

Answer 1

Before the alert, do clearInterval(timer);, where timer is the ID of that timer with createBall.