26384 2014-07-18 19:23:44 +0000 Structure cloning Map and Set objects: what should get cloned? 2016-02-29 21:24:51 +0000 1 1 1 Unclassified WHATWG HTML unspecified Other other RESOLVED MOVED blocked waiting for JS spec to define structured cloning P3 normal Unsorted 1 evilpies ian adamk annevk bobbyholley ian jorendorff mike contributor oldest_to_newest 109090 0 evilpies 2014-07-18 19:23:44 +0000 I would like to have a confirmation that cloning the "object properties" on Map and Set is really intentional. I don't think that is particularly useful behavior. In my first (non-specification based) implementation I didn't even consider that possibility. https://bugzilla.mozilla.org/show_bug.cgi?id=1036136 109091 1 jorendorff 2014-07-18 19:27:18 +0000 It's also a little surprising because the spec doesn't clone expando properties of Dates or Arrays. Always cloning expandos would at least be consistent. 109112 2 ian 2014-07-19 16:46:26 +0000 The current text is more or less a placeholder. I expect eventually the cloning of native JS types to be defined in JS proper. 110205 3 bobbyholley 2014-08-15 00:37:11 +0000 With my security hat on, I would vastly prefer to not clone expandos (and only do so for Object and Array). I can explain why if needed, but it sounds like nobody's really in disagreement here. 120373 4 adamk 2015-05-19 21:14:00 +0000 The current spec text is in terms of [[MapData]] and [[SetData]], which looks correct to me. Should this issue be marked as resolved? 122862 5 annevk 2015-08-28 15:41:13 +0000 Indeed. 125298 6 annevk 2016-02-29 21:24:51 +0000 The text was indeed wrong and is unfortunately still wrong. This is now https://github.com/whatwg/html/issues/754 and I hope to fix it soon.