Core logic for a bitwise tic-tac-toe board checker

tic-tac-toe.js

function flatten(arrays) {
  return [].concat.apply([], arrays)
}

function zip(...arrays) {
  let zipped = []
  for(var index = 0; index < arrays[0].length; index++){
    zipped.push(arrays.map(a => a[index]))
  }
  return zipped
}

function equals(a, b) {
    var i = a.length;
    if (i != b.length) return false;
    while (i--) {
        if (a[i] !== b[i]) return false;
    }
    return true;
}

function bitwiseAnd(a, b) {
  return zip(a, b).map(([bitA, bitB]) => bitA & bitB)
}

const winningBitboards = [
    [1, 1, 1,
     0, 0, 0,
     0, 0, 0],

    [0, 0, 0,
     1, 1, 1,
     0, 0, 0],

    [0, 0, 0,
     0, 0, 0,
     1, 1, 1],

    [1, 0, 0,
     1, 0, 0,
     1, 0, 0],

    [0, 1, 0,
     0, 1, 0,
     0, 1, 0],

    [0, 0, 1,
     0, 0, 1,
     0, 0, 1],

    [1, 0, 0,
     0, 1, 0,
     0, 0, 1],

    [0, 0, 1,
     0, 1, 0,
     1, 0, 0]
]

// takes a vector board with vector rows of symbols/strings/ints, or a sring board,
// returns a bitboard for the given sign
function compileBitboard(board, sign) {
  board = (typeof(board) == 'string')
    ? board = board.replace(/\s/g, '').split('')
    : flatten(board)
  return board.map(c => Number(c === sign))
}



// returns true if the given bitboard contains one of the states in the second argument
function bitboardStatematch(bitboard, [firstState, ...states]) {
  return Boolean(equals(bitwiseAnd(bitboard, firstState), firstState) ||
    (states.length && bitboardStatematch(bitboard, states)))
}


function isBitVictory(bitboard) {
  return bitboardStatematch(bitboard, winningBitboards)
}

function isVictory(board, sign) {
  return isBitVictory(compileBitboard(board, sign))
}

console.log(isVictory([
  ["x", "o",  null],
  ["x",  null, "o"],
  ["x",  "o", null]
], "x"))

console.log(isVictory(" ono\n xon\n xno", "o"))

const otherInputs = [
  [[[1  0  null] [1  null 0 ] [1  0  null]], 1], // ture
  [[["x" "o" null] ["x" null "o"] ["x" "o" null]] "o"]  // false
]

js adaption of an old clojure sample