That's because when you're putting that into the Chrome console, you're short-circuiting it. It's just printing 'OK' because it's reaching the default case, not actually returning something.

If you want something returned, stick it in a function, and return the 'OK' from in the default case.

function switchResult(a){

    switch(a){

        default: 

            return OK;

    }

}



var a = switchResult(3);