Coding Challenge Given a number suffixed in a URL, render a grid of size n, e.g. http://localhost/n Clicking an empty square adds an 'x' to it. Clicking a square with an x toggles it back to blank. X's are draggable to any other square in the grid. If an x is dropped in a square already containing an x, the drag is canceled. Grid changes are synced in real time across all other clients accessing the same URL. Must work on mobile with touch screens. No third party javascript libraries.
