Tic Tac Toe in JS

game.js

/*
Cassidy Brooke - Recurse Center
Written in JavaScript, Node
July 6, 2019
*/


// this is required to take terminal inputs in Node.js
const readline = require('readline');
const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});


// welcome message
console.log('\n');
console.log('******************************');
console.log('*       Tic-Tac-Toe          *');
console.log('******************************');
console.log('\n');
console.log('How to play:' + '\n' + 'Select a square on your turn.' + '\n' + 'Player to get three vertically, horizontally or diagonally in a row wins.' + '\n');


// store board state in data structure
board = {
  'top-L': ' ', 'top-M': ' ', 'top-R': ' ',
  'mid-L': ' ', 'mid-M': ' ', 'mid-R': ' ',
  'bot-L': ' ', 'bot-M': ' ', 'bot-R': ' '
}


// print board state to console
function drawBoard(board) {
  console.log(board['top-L'] + '|' + board['top-M'] + '|' + board['top-R']);
  console.log('-+-+-');
  console.log(board['mid-L'] + '|' + board['mid-M'] + '|' + board['mid-R']);
  console.log('-+-+-');
  console.log(board['bot-L'] + '|' + board['bot-M'] + '|' + board['bot-R']);
}


// possible winning combos
function checkForWinner(board, turn) {

  if ((board['top-L'] === winner && board['top-M'] === winner && board['top-R'] == winner) ||
      (board['mid-L'] === winner && board['mid-M'] === winner && board['mid-R'] == winner) ||
      (board['bot-L'] === winner && board['bot-M'] === winner && board['bot-R'] == winner) ||
      (board['top-L'] === winner && board['mid-L'] === winner && board['bot-L'] == winner) ||
      (board['top-M'] === winner && board['mid-M'] === winner && board['mid-R'] == winner) ||
      (board['top-R'] === winner && board['mid-M'] === winner && board['bot-R'] == winner) ||
      (board['top-L'] === winner && board['mid-M'] === winner && board['bot-R'] == winner) ||
      (board['bot-L'] === winner && board['mid-M'] === winner && board['top-R'] == winner)) {
    return true
  } else {
    return false
  }
}


// initialize blank board for first turn
drawBoard(board);
let won = false;
let winner;
let turn = 'X';
let move;


function processInput() {
  rl.question('\n' + 'Turn for ' + turn + '. Your move: ', function(move) {
    winner = turn;
    won = checkForWinner(board, winner);

    if (won === true) {
      console.log('Game over: Player ' + winner + ' wins the game!')
      rl.close();
    } else {
      board[move] = turn;
      if (turn === 'X') {
        turn = 'O';
      } else {
        turn = 'X';
      };
      drawBoard(board);
      processInput();
    }
  });
}
processInput();