Simply stuck with this one, any help would be appreciated.

I have an associative array like this:

```
var player = {
  source: {
    item1: value,
    item2: value,
    item3: {
      item3-1: value
    }
  },
  playback: {
    parameter1: value,
    parameter2: value,
  }
}

```

What I'm trying to do is add values into player.source like this:

```
player.source.item4.item4-1 = 'something'

```

such that player.source looks like this:

```
  source: {
    item1: value,
    item2: value,
    item3: {
      item3-1: value
    },
    item4: {
      item4-1: 'something',
    },
  },

```

Thanks in advance for your help.