23529 2013-10-15 22:23:46 +0000 Behavior of CSS.escape(undefined) 2013-10-16 10:56:07 +0000 1 1 1 Unclassified CSS CSSOM unspecified PC All RESOLVED WONTFIX P2 normal --- 1 zcorpan zcorpan public-css-bugzilla oldest_to_newest 94798 0 zcorpan 2013-10-15 22:23:46 +0000 http://dev.w3.org/csswg/cssom/#the-css.escape()-method [[ escape(DOMString ident) ]] Consider returning "undefined" instead of throwing. http://krijnhoetmer.nl/irc-logs/whatwg/20131015#l-485 http://krijnhoetmer.nl/irc-logs/whatwg/20131016 94819 1 zcorpan 2013-10-16 10:56:07 +0000 I had misunderstood WebIDL. The current behavior is as follows: CSS.escape() throws TypeError. CSS.escape(undefined) returns "undefined" This is consistent with other DOM methods like e.g. document.getElementById. However, it's inconsistent with JS functions like encodeURIComponent which makes omitted argument also return "undefined". The pro-throwing argument is mainly that it's easier to debug an error like CSS.escape(someobject.propertyThatDoesntExist) However, no other method that takes a DOMString seems to throw for that case. I think this settles that CSS.escape(undefined) should return "undefined". What to do for CSS.escape() without argument is less clear (be consistent with encodeURIComponent or with document.getElementById). But also seems less important. Let's stick with WebIDL's default for that case.