Determine audio or video upon import

I'm coding a Premiere plugin using the SDK provided by Adobe. I want my function to be able to be sensitive to whether the media is audio only or video (with or without audio), e.g. whether it's a .wav or a .mp4. I want this to happen before any clips are on any timelines, so I can't use the track.mediaType attribute.

I am trying to do this when the media is a project item but am not finding anything in the documentation (https://premiere-scripting-guide.readthedocs.io/4%20-%20Project%20Item%20object/projectItem.html?highlight=mediaType)

For now, this is what I'm doing:

GetProjectItemType: function (projectItem){
        if (projectItem.name.includes("wav") || projectItem.name.includes("mp3") || projectItem.name.includes("AIFF") )
            return "Audio"; 
        else
            return "Video"; 
    }

Is there a way to accomplish this? Thanks!