Media query detection

This gist from Nicholas C. Zakas looks really handy:

This function determines if the browser is currently in a particular media media mode. Use the same media query as you would in CSS or on a <link> element.

I can see myself using it quite a bit. His usage examples look like this:

if (isMedia("screen and (max-width:800px)"){
    //do something for the screen
}

if (isMedia("all and (orientation:portrait)")){
    //react to portrait mode
}

I’m thinking it might be even more useful for me to detect !isMedia('something) and fallback to js stuff in those cases. Not sure yet. Still need to ponder.