if ` id ` is empty it will throw a HTML validation error, maybe worth to do a check if it's set somehow?

http://validator.w3.org/check?verbose=1&uri=https%3A%2F%2Fdeveloper.mozilla.org%2Fen-US%2FFirefox 
"Line 144, Column 56: Bad value for attribute id on element body: An ID must not be the empty string."