Minesweeper LeetCode solution in JavaScript

1
var updateBoard = function (board, click) {
2
  const rows = board.length;
3
  const cols = board[0].length;
4
  dfs(click[0], click[1]);
5
  return board;
6

7
  function dfs(i, j) {
8
    if (!board[i][j]) return;
9
    if (board[i][j] === "M") {
10
      board[i][j] = "X";
11
      return;
12
    }
13
    if (board[i][j] !== "E") return;
14

15
    const mines = checkForMine(i, j); // Check for mines
16

17
    if (mines) {
18
      board[i][j] = mines.toString();
19
      return;
20
    } else {
21
      // If we haven't got mines, check another cells
22
      board[i][j] = "B";
23
      for (let x = Math.max(i - 1, 0); x < Math.min(i + 2, rows); x++) {
24
        for (let y = Math.max(j - 1, 0); y < Math.min(j + 2, cols); y++) {
25
          dfs(x, y);
26
        }
27
      }
28
    }
29
  }
30

31
  function checkForMine(x, y) {
32
    let mines = 0;
33
    for (let i = Math.max(x - 1, 0); i < Math.min(x + 2, rows); i++) {
34
      for (let j = Math.max(y - 1, 0); j < Math.min(y + 2, cols); j++) {
35
        if (board[i][j] === "M") mines++;
36
      }
37
    }
38
    return mines;
39
  }
40
};