Terminal Tic Tac Toe (tttt)

tic-tac-toe.js

const prompt = require("prompt");
prompt.start();

const state = [
  [" ", " ", " "],
  [" ", " ", " "],
  [" ", " ", " "],
];

const printBoard = (state) => {
  console.log("\n");
  state.forEach((row, i) => {
    console.log(row.join("|"));
    if (i < 2) {
      console.log("-----");
    }
  });
  console.log("\n");
};

const gameLoop = (isX) => {
  printBoard(state);
  prompt.get(["move"], function (err, result) {
    const move = result.move;
    const [row, col] = move.split(",");

    if (row < 0 || row > 2 || col < 0 || col > 2) {
      console.log(
        "Invalid move. Please format move as 0-2,0-2. For example, 1,1"
      );
      gameLoop(isX);
      return;
    }

    if (state[row][col] !== " ") {
      console.log("Invalid move. That cell is already taken.");
      gameLoop(isX);
      return;
    }
    state[row][col] = isX ? "X" : "O";

    if (checkWinner(state)) {
      console.log(isX ? "X" : "O", "wins!");
      printBoard(state);
      return;
    }

    if (checkDraw(state)) {
      console.log("Draw!");
      printBoard(state);
      return;
    }

    gameLoop(!isX);
  });
};

const checkDraw = (state) => {
  // check if every cell is filled
  // if so, return true
  // this means all moves have been taken, and we have no winner, so draw
  return state.every((row) => row.every((cell) => cell !== " "));
};

checkWinner = (state) => {
  for (let i = 0; i < 3; i++) {
    if (
      state[i][0] === state[i][1] &&
      state[i][1] === state[i][2] &&
      state[i][0] !== " "
    ) {
      return true;
    }

    if (
      state[0][i] === state[1][i] &&
      state[1][i] === state[2][i] &&
      state[0][i] !== " "
    ) {
      return true;
    }

    if (
      state[0][0] === state[1][1] &&
      state[1][1] === state[2][2] &&
      state[0][0] !== " "
    ) {
      return true;
    }

    if (
      state[0][2] === state[1][1] &&
      state[1][1] === state[2][0] &&
      state[0][2] !== " "
    ) {
      return true;
    }
  }

  return false;
};

gameLoop(true);