Starting Point for Conway's Game of Life

gameOfLife.js

function gameOfLifeIterator(board) {
  let returnBoard = [];

  for (let i = 0; i < board.length; i++) {
    returnBoard[i] = [];

    for (let j = 0; j < board[i].length; j++) {
      let neighborCount = getCellNeighborCount(i, j, board);

      if (board[i][j] === 1) {
        if (neighborCount > 1 && neighborCount < 4) {
          returnBoard[i][j] = 1;
        } else {
          returnBoard[i][j] = 0;
        }
      } else {
        returnBoard[i][j] = (neighborCount === 3) ? 1 : 0;
      }
    }
  }

  return returnBoard;

  function getCellNeighborCount(x, y, board) {
    let neighborCount = 0;

    if (board[x - 1] !== undefined) {
      if (board[x - 1][y - 1] === 1) {
        neighborCount++;
      }
      if (board[x - 1][y] === 1) {
        neighborCount++;
      }
      if (board[x - 1][y + 1] === 1) {
        neighborCount++;
      }
    }

    if (board[x] !== undefined) {
      if (board[x][y - 1] === 1) {
        neighborCount++;
      }
      if (board[x][y + 1] === 1) {
        neighborCount++;
      }
    }

    if (board[x + 1] !== undefined) {
      if (board[x + 1][y - 1] === 1) {
        neighborCount++;
      }
      if (board[x + 1][y] === 1) {
        neighborCount++;
      }
      if (board[x + 1][y + 1] === 1) {
        neighborCount++;
      }
    }

    return neighborCount;
  }
}