Cannot use nuxt.js helper 

Can I use [$nuxt: The Nuxt.js helper](https://nuxtjs.org/docs/2.x/internals-glossary/$nuxt) functions with nuxt7?

Currently, I have tried 

```
$nuxt.isOffline
$nuxt.isOnline
$nuxt.$loading.start()
$nuxt.$loading.stop()
```

and they are not working.

Is there any way to access those functions? Or these functions couldn't be accessed by design?