[Algorithm] Print 2-D array in spiral order

dir = (dir+1) % 4

  let results = [],
        dir = 0, //0: left -> right, 1: top -> bottom, 2: right -> left, 3: bottom -> top
        top = 0,
        bottom = arys.length - 1,
        left = 0,
        right = arys[0].length - 1;

function PrintSpiralOrder (arys) {
  let results = [],
        dir = 0, //0: left -> right, 1: top -> bottom, 2: right -> left, 3: bottom -> top
        top = 0,
        bottom = arys.length - 1,
        left = 0,
        right = arys[0].length - 1;
  
  while (top <= bottom && left <= right) {
     if (dir === 0) {
       for (let i = left; i <= right; i++) {
         results.push(arys[top][i]);
       }
       top++;
     } else if (dir === 1) {
       for (let i = top; i <= bottom; i++) {
         results.push(arys[i][right]);
       }
       right--;
     } else if (dir === 2) {
       for (let i = right; i >= left; i--) {
         results.push(arys[bottom][i]);
       }
       bottom--;
     } else if (dir === 3) {
       for (let i = bottom; i >= top; i--) {
         results.push(arys[i][left]);
       }
       left++;
     }
    
     dir = (dir + 1) % 4;
  }
  
  return results;
}

const data = [
  [2,4,6,8],
  [5,9,12,16],
  [2,11,5,9],
  [3,2,1,8]
];

const res = PrintSpiralOrder(data);
console.log(res); // [ 2, 4, 6, 8, 16, 9, 8, 1, 2, 3, 2, 5, 9, 12, 5, 11 ]