No need for typeof here. One of the following might be better:

```javascript
value == null
value === void 0
value === undefined
arguments.length == 0
```

@MatthewMueller, what's your stance on treating null and undefined differently? And do you prefer to switch on the number of arguments or on the value of the first argument? In other words, how should each of the following be handled?

```javascript
$input.val()
$input.val(null)
$input.val(undefined)
```