Rotate Matrix in JavaScript

rotateMatrix.js

// time and space complexity of O(n2) and O(1) respectively
const rotateImage = (matrix) => {
  if (!matrix.length || !matrix[0].length) return [];
  
  const len = matrix.length;
  
  // transpose matrix
  for (let i = 0; i < len; i++) {
    for (let j = i; j < len; j++) {
      const curr = matrix[i][j];
      
      matrix[i][j] = matrix[j][i];
      matrix[j][i] = curr;
    }
  }
  
  const middle = Math.floor(len / 2);
  
  // swap left-most value with right-most value until middle is reached
  for (let i = 0; i < len; i++) {
    for (let j = 0; j < middle; j++) {
      const curr = matrix[i][j];
      const endPos = len - 1 - j;
      
      matrix[i][j] = matrix[i][endPos];
      matrix[i][endPos] = curr;
    }
  }
  
  return matrix;
};