tictactoe.js

let chalk = require("chalk");
let prompt = require("prompt-sync")();
let board = [
  [" ", " ", " "],
  [" ", " ", " "],
  [" ", " ", " "]
];
let player = true, marker, icon, win = false;

function promptplayer() {
  let playername;
  if (player) {
    playername = "Player 1";
    icon = "⨯";
  } else if (!player) {
    playername = "Player 2";
    icon = "⚬";
  };
  marker = prompt(`${chalk.red(playername)} (${chalk.magenta(icon)}) please enter your marker's placement: `);
  console.log();
};

function changeboard() {
  if (!(/([0-2],[a-c])/g.test(marker))) {
    if (player) {
      player = false;
    } else if (!player) {
      player = true;
    };
    return console.log("Invalid format, try again.\n");
  };
  let newm = marker.split(",");
  if (newm[1] == "a") {
    newm[1] = 0;
  } else if (newm[1] == "b") {
    newm[1] = 1;
  } else if (newm[1] == "c") {
    newm[1] = 2;
  };
  if (player) {
    icon = "⨯";
  } else if (!player) {
    icon = "⚬";
  };
  if (board[newm[0]][newm[1]] == " ") {
    board[newm[0]][newm[1]] = icon;
  } else {
    nextplayer();
    console.log("That spot's taken! Try again.\n");
  };
};

function nextplayer() {
  player = !player;
};

function printboard() {
  console.log(`   a   b   c\n0  ${chalk.magenta(board[0][0])} | ${chalk.magenta(board[0][1])} | ${chalk.magenta(board[0][2])}\n  -----------\n1  ${chalk.magenta(board[1][0])} | ${chalk.magenta(board[1][1])} | ${chalk.magenta(board[1][2])}\n  -----------\n2  ${chalk.magenta(board[2][0])} | ${chalk.magenta(board[2][1])} | ${chalk.magenta(board[2][2])}\n`);
};

function checkwin() {
  let winner;
  if (board[0][0] == "⨯" && board[0][1] == "⨯" && board[0][2] == "⨯") {
    winner = "⨯";
    win = true;
  } else if (board[0][0] == "⚬" && board[0][1] == "⚬" && board[0][2] == "⚬") {
    winner = "⚬";
    win = true;
  } else if (board[1][0] == "⨯" && board[1][1] == "⨯" && board[1][2] == "⨯") {
    winner = "⨯";
    win = true;
  } else if (board[1][0] == "⚬" && board[1][1] == "⚬" && board[1][2] == "⚬") {
    winner = "⚬";
    win = true;
  } else if (board[2][0] == "⨯" && board[2][1] == "⨯" && board[2][2] == "⨯") {
    winner = "⨯";
    win = true;
  } else if (board[2][0] == "⚬" && board[2][1] == "⚬" && board[2][2] == "⚬") {
    winner = "⚬";
    win = true;
  } else if (board[0][0] == "⨯" && board[1][0] == "⨯" && board[2][0] == "⨯") {
    winner = "⨯";
    win = true;
  } else if (board[0][0] == "⚬" && board[1][0] == "⚬" && board[2][0] == "⚬") {
    winner = "⚬";
    win = true;
  } else if (board[0][1] == "⨯" && board[1][1] == "⨯" && board[2][1] == "⨯") {
    winner = "⨯";
    win = true;
  } else if (board[0][1] == "⚬" && board[1][1] == "⚬" && board[2][1] == "⚬") {
    winner = "⚬";
    win = true;
  } else if (board[0][2] == "⨯" && board[1][2] == "⨯" && board[2][2] == "⨯") {
    winner = "⨯";
    win = true;
  } else if (board[0][2] == "⚬" && board[1][2] == "⚬" && board[2][2] == "⚬") {
    winner = "⚬";
    win = true;
  } else if (board[0][0] == "⨯" && board[1][1] == "⨯" && board[2][2] == "⨯") {
    winner = "⨯";
    win = true;
  } else if (board[0][0] == "⚬" && board[1][1] == "⚬" && board[2][2] == "⚬") {
    winner = "⚬";
    win = true;
  } else if (board[2][0] == "⨯" && board[1][1] == "⨯" && board[0][2] == "⨯") {
    winner = "⨯";
    win = true;
  } else if (board[2][0] == "⚬" && board[1][1] == "⚬" && board[0][2] == "⚬") {
    winner = "⚬";
    win = true;
  } else if (!board.some(row => row.includes(" "))) {
    win = true;
    return console.log(`It's a draw! ${chalk.blue("∞")}`);
  };
  if (win) console.log(`${chalk.magenta(winner)} won the game!`);
};

console.log(`Welcome to Tic-Tac-Toe!\n\n${chalk.red("Player 1")} will go first as ${chalk.magenta("⨯")}, and ${chalk.red("Player 2")} will go second as ${chalk.magenta("⚬")}.\n\nHere is the starting board:\n`);
printboard();
console.log(`Please format your marker placements as ${chalk.blue("number")},${chalk.blue("letter")} coordinates including the comma between them.\n\nOn that note, let the games begin!\n`);

while (!win) {
  promptplayer();
  changeboard();
  nextplayer();
  printboard();
  checkwin();
};