Unique Paths (Recursion)

let uniquePaths = function(m, n) {
    let results = new Set();
    function getPath(row, col, path = '') {
        if (row >= m && col >= n) {
            results.add(path);
            return;
        }

        if (row === m) {
            // go right if at the bottom row
            getPath(row, col + 1, path + 'R');
        }
        else if (col === n) {
            // go down if at the end column
            getPath(row + 1, col, path + 'D');
        }
        else {
            // go down and go right
            getPath(row, col + 1, path + 'R');
            getPath(row + 1, col, path + 'D');
        }
    }

    getPath(1, 1, 'S');
    return results.size;
};