Technically `'\08'` is an malformed string literal (as per the current spec), and although it seems to work fine in some environments it does throw a SyntaxError in strict mode in IE/Chakra, Safari/JavaScriptCore, and Firefox/SpiderMonkey (as it’s considered to be an octal escape sequence there for some reason).

For a minifier like UglifyJS I’d prefer this safer version that includes all digits.