before-variable-renaming.js

function gameOfLifeIterator(board) {
  const isAlive = (x, y) => board[x] && board[x][y]

  return board.map((row, x) =>
    row.map((_, y) => {
      let n = getCellNeighborCount(x, y)
      return (isAlive(x, y) ? n > 1 && n < 4 : n === 3) ? 1 : 0
    }))

  function getCellNeighborCount (x, y) {
    let neighborCount = 0
    if (isAlive(x - 1, y - 1)) neighborCount++
    if (isAlive(x - 1, y)) neighborCount++
    if (isAlive(x - 1, y + 1)) neighborCount++
    if (isAlive(x, y - 1)) neighborCount++
    if (isAlive(x, y + 1)) neighborCount++
    if (isAlive(x + 1, y - 1)) neighborCount++
    if (isAlive(x + 1, y)) neighborCount++
    if (isAlive(x + 1, y + 1)) neighborCount++
    return neighborCount
  }
}