如何在Javascript中转置存储为一维数组的二维方阵

function transposeArray(arr) {
  var n = arr.length;
  var row = Math.floor(Math.sqrt(n));
  var col = Math.ceil(n / row);
  var matrix = [];

  for (var i = 0; i < row; i++) {
    matrix[i] = [];
    for (var j = 0; j < col; j++) {
      var index = i + j * row;
      if (index < n) {
        matrix[i][j] = arr[index];
      } else {
        matrix[i][j] = undefined; // 如果一维数组长度不是方阵的话，用undefined填充空位
      }
    }
  }

  return matrix;
}

// 示例用法
var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9];
var result = transposeArray(arr);
console.log(result);

[ [1, 2, 3],
  [4, 5, 6],
  [7, 8, 9] ]