In javascript, I needed to compare the "for" attribute of a LABEL with the ID of an input object to see if I'm looking at the LABEL associated with that radio button / checkbox.
Programmatically, it doesn't work to say something like
if( theLabel.for == theRadio.id )
because for is a reserved word in javascript.
So after some investigation (spitting out every single property of the LABEL element and looking to see how the "for" is referred to programmatically), I learned that the way to refer to the FOR attribute with JavaScript is with the htmlFor property:
if( theLabel.htmlFor == theRadio.id )