Minimum Path Sum (Recursion)

let minPathSum = function(grid) {

    if(!grid || !grid.length) return 0;

    let maxRow = grid.length, maxCol = grid[0].length;
    function sum(row, col, total, path = '') {
        const val = grid[row][col] + total; //?
        if (row === maxRow - 1 && col === maxCol - 1) {
            return val;
        } //?

        if (row === maxRow - 1) {
            return sum(row, col + 1, val);
        }
        else if (col === maxCol - 1) {
            return sum(row + 1, col, val);
        } else {
            const down = sum(row + 1, col, val);
            const right = sum(row, col + 1, val);
            return Math.min(down, right);
        }
    }

    return sum(0, 0, 0);
};