Recursive unique javascript method?

Question

I have an array in this form ...

arr[itemDescription]
- [0] someValue1
- [1] someotherValue1
arr[itemDescription]
- [0] someValue2
- [1] someotherValue2
arr[itemDescription]
- [0] someValue3
- [1] someotherValue3
....

Now i would like to generate all possible variations where i have an array with the first item combined with the other elements, the second element combined with the other elements and so on. Like:

[someValue1][someValue2][someValue3]
[someValue1][someotherValue2][someValue3]
[someValue1][someotherValue2][someotherValue3]
....

to sum up, for the folowing input array:

[[11, 12], [21, 22], [31, 32]];

I need to obtain an output array like

[[11, 21, 31], [11, 21, 32], [11, 22, 31], [11, 22, 32], [12, 21, 31], [12, 21, 32], [12, 22, 31], [12, 22, 32]];

Can somebody help me how I would do that in javascript?

Thank you a lot!

What did you try so far? Put down some code or you're gonna get downvotes. — TigOldBitties, Dec 12 '16 at 07:46
Welcome to SO. Please visit the [help] and take the [tour] to see what and how to ask. HINT: Post effort and code — mplungjan, Dec 12 '16 at 07:46
Possible duplicate of [Finding All Combinations of JavaScript array values](http://stackoverflow.com/questions/4331092/finding-all-combinations-of-javascript-array-values) — Developer, Dec 12 '16 at 15:16

score 0 · Accepted Answer · answered Dec 12 '16 at 17:06

I propose this solution. To decide to choose the index of sub array iside input array, I use array dimension modulo global index :

var input = [[11, 12], [21, 22], [31, 32]];
var dim = Math.pow(2, input.length);
var output = new Array(dim);
output.fill(0);
input.forEach((x,i) => {
  var limit = dim / Math.pow(2, i+1);
  output.forEach((y,j,arr) => {
    var index = Math.floor((j+1)/limit) % 2;
    if (i === 0)
      arr[j] = [x[index]];
    else
      arr[j].push(x[index]);
  });
});
console.log(output);

Recursive unique javascript method?

1 Answers1