Check browser user-agent inside a trigger

Hi,

I am working on custom mute/unmute logic and as per the requirement, if user is viewing the course using a handheld device (e.g. tablet), then mute/unmute button should be hidden. In case of a PC, it should be visible.

Logic will be something like following.

on timeline starts -->

if (user-agent is desktop)

{

  change state of --> mute-unmute-btn --> normal

}

on timeline starts -->

if (user-agent is tablet/mobile)

{

  change state of --> mute-unmute-btn --> hidden

}

My query is, how can I get user-agent value inside a trigger?

Thanks in advance

MK