`date.getDay()` counts from zero, day `7` does not exist:

```
> d = new Date('Sunday Aug 25 2013 10:10:10 GMT+0200 (SAST)');
Sun Aug 25 2013 10:10:10 GMT+0200 (SAST)
> d.getDay();
0
> d = new Date('Saturday Aug 24 2013 10:10:10 GMT+0200 (SAST)');
Sat Aug 24 2013 10:10:10 GMT+0200 (SAST)
> d.getDay();
6
>
```