Simple function to turn simple arrays to multidimensional. Found here: http://stackoverflow.com/questions/4492385/how-to-convert-simple-array-into-two-dimensional-arraymatrix-in-javascript-or

matrix.js

function listToMatrix(list, elementsPerSubArray) {
  var matrix = [], i, k;

  for (i = 0, k = -1; i < list.length; i++) {
    if (i % elementsPerSubArray === 0) {
      k++;
      matrix[k] = [];
    }

    matrix[k].push(list[i]);
  }

  return matrix;
}

var matrix = listToMatrix([1, 2, 3, 4, 4, 5, 6, 7, 8, 9], 3);
// result: [[1, 2, 3], [4, 5, 6], [7, 8, 9]]