transpose

var transpose = function (matrix) {
  var result = [];
  for (var i = 0; i < matrix.length; i++) {
    for (var j = 0; j < matrix[i].length; j++) {
      if (result[j] == undefined) result[j] = [];
      result[j][i] = matrix[i][j];
    }
  }
  return result
}