Its an AMD thing - module ids don't have file extensions. They may or may not relate to a filename e.g. in `a.js`:

```javascript
define(function() {
...
})
```

would implicitly declare "a" as the module id. However if `a.js` contained:

```javascript
define("somethingelse", function() {
...
})
```

...then the module id would be `somethingelse`.