javascript array spiral

1function(A){
2        let retArray = [];
3        let T = 0;
4        let B = A.length - 1;
5        let L = 0;
6        let R = A[0].length - 1;
7        let d = 0;
8        
9        while (T <= B && L <= R) {
10            if (d === 0) {
11                for (let i = L; i <= R; i++) {
12                    retArray.push(A[T][i]);
13                }
14                T++;
15                d = 1;
16            } else if (d === 1) {
17                for (let i = T; i <= B; i++) {
18                    retArray.push(A[i][R]);
19                }
20                R--;
21                d = 2;
22            } else if (d === 2) {
23                for (let i = R; i >= L; i--) {
24                    retArray.push(A[B][i]);
25                }
26                B--;
27                d = 3;
28            } else if (d === 3) {
29                for (let i = B; i >= T; i--) {
30                    retArray.push(A[i][L]);
31                }
32                L++;
33                d = 0;
34            }
35        }
36        
37        return retArray;
38    }