list to matrix

list-to-matrix.js

const listToMatrix = (list) => {
  let matrix = [], i, k;
  for (i = 0, k = -1; i < list.length; i++) {
    if (i % 2 === 0) {
      k++;
      matrix[k] = [];
    }
    matrix[k].push(list[i]);
  }
  return matrix;
};