This line can be removed by adding var in front of the 2 next lines:
```JavaScript
var $firstButton = self.$picker.find('[role=button]').first();
var $lastButton = self.$picker.find('[role=button]').last();
```

Even better I think:

```JavaScript
var $buttons = self.$picker.find('[role=button]');
var $firstButton = $buttons.first();
var $lastButton = $buttons.last();
```