Multiply arrays in an array

multiplyArray.coffee

multiply: (a, n) ->

  i = 0
  while i < a.length
    j = 0
    while j < n - 1
      a[i] = a[i].concat(a[i])
      j++
    i++
  a

multiplyArray.js

var a = [
  ["a", "b", "c"],
  ["d", "e"],
  ["f"]
];

//multiply (clone?) arrays of an array
var ma = function(a, n) {
  for (var i = 0; i < a.length; i++) {
    for (var j = 0; j < n - 1; j++) {
      a[i] = a[i].concat(a[i]);
    }
  }
  return a;
}

/*
    same same, but separate functions */
*/

// multiply an array
var m = function(a, n) {
  for (var i = 0; i < n - 1; i++) {
    a = a.concat(a);
  }
  return a;
};

// do something with each array in an array n times
var ma = function(a, n) {
  for (var i = 0; i < a.length; i++) {
    a[i] = m(a[i], n);
  }
  return a;
}

console.log(ma(a, 2));

multiplyArray.rb

n=2; [("a".."c").to_a, ("d".."g").to_a, ("h".."i").to_a, ["j"]].map{|x| x*n}