I tried to figure this out multiple ways but it looks like my Javascript abilities are not quite there yet. I have a 2D array that includes some true and false elements. The idea is to join the last 4 elements of each array within the 2D array into a string, but removing any false values:

Original Array

```
var data = [
  ['apple', false, 1, false, 2, 5],
  ['orange',true,  2, 5, false, 2],
  ['pear',true, 3, 7, false, false]
  ];

```

Desired result:

```
var data = [
  ['apple', false, "1, 2, 5"],
  ['orange',true,  "2, 5, 2"],
  ['pear',true, "3, 7"]
  ];

```

Any ideas how I can go about this?