Append value to multidimensional array

Question

function append (array, value, dimension) {
  switch (dimension) {
    case 0:
      array.push( value );
      break;
    case 1:
      array[array.length-1].push( value );
      break;
    case 2:
      array[array.length-1][array[array.length-1].length-1].push( value );
      break;
    case 3:
      array[array.length-1][array[array.length-1].length-1][array[array[array.length-1].length-1].length-1].push( value );
      break;
  }
  return array;
}


append([0,1], 9, 0) // [0,1,9]
append([0,[1]], 9, 0) // [0,[1],9]
append([0,[1]], 9, 1) // [0,[1,9]]
append([1,[2,[3,[4]]]], 9, 3) // [1,[2,[3,[4,9]]]]
append([1,[2,[3],2,[4]]], 9, 2) // [1,[2,[3],2,[4,9]]]

This function works right only if dimension ≤ 3. Also, it is very ugly. What a proper way to do it?

UPDATE:
I know how to recursively get last element of array:

function get_last(array, dimension) {
  return dimension === 0 ? array[array.length-1] : get_last(array[array.length-1], dimension-1);
}

I need append.

Answer 1

A recursive algorithm will follow along these lines:

Base Case: Append to 0th dimension, Just do it.
Recursive Case: Append to nth dimension where n > 0, Append to n-1 dimension

Along the way you have to ensure that the values accepted by your function are sensible.

UPDATE: You can try this:

 function append2(array, value, dimension){
    if(dimension == 0){
       array.push( value );
    }else{
       append(array[array.length-1], value, dimension - 1);
    }

    return array;
  }

This has not been exhaustively tested so be careful.

Answer 2

Try this iterative algorithm:

function append(array, value, level) {
    var tmp = array;
    while (level > 0) {
        for (var i=tmp.length; i>=0; --i) {
            if (tmp[i] instanceof Array) {
                tmp = tmp[i];
                level--;
                break;
            }
        }
        if (i < 0) {
            break;
        }
    }
    tmp.push(value);
    return array;
}

Answer 3

Array.prototype.append = function (aElem, aDim) {
  if (aDim > 0) {
    this[this.length - 1].append(aElem, aDim - 1);
  } else {
    this.push(aElem);
  }

  return this;
}

then

a = [0,[1,2]]; a.append(9, 0) // [0,[1,2],9]
a = [0,[1,2]]; a.append(9, 1) // [0,[1,2,9]]
a = [1,[2,[3,[4]]]]; a.append(9, 3) // [1,[2,[3,[4,9]]]]
...

(tested under rhino)

Answer 4

from my understanding, you always append to the last and deepest array. If yes, there's no need to provide a dimension explicitly

lastArray = function(a) {
  var p = a[a.length - 1];
  return p.push ? lastArray(p) : a;

}

r = [1, 2, [3, [4, 5]]]
lastArray(r).push(9)
console.log(r) // [1, 2, [3, [4, 5, 9]]]