Number of Closed Islands

/**
 * @param {number[][]} grid
 * @return {number}
 */
var closedIsland = function(grid) {
    const rows = grid.length;
    const cols = grid[0].length;

    const explore = (id, row, col) => {
        if (row < 0 || row >= rows || col < 0 || col >= cols) return false;
        if (grid[row][col] === 1 || grid[row][col] === id) return true;
        if (grid[row][col] !== 0) return false;

        grid[row][col] = id;

        const temp = explore(id, row, col + 1) &&
            explore(id, row + 1, col) &&
            explore(id, row, col - 1) &&
            explore(id, row - 1, col);

        if (!temp) {
            grid[row][col] = -1;
        }

        return temp;
    };

    let res = 0;

    for (let row = 0; row < rows; row++) {
        for (let col = 0; col < cols; col++) {
            if (grid[row][col] === 0) {
                if (explore(res + 2, row, col)) {
                    res++;
                }
            }
        }
    }

    return res;
};