28978 2015-07-20 20:40:32 +0000 The order of forEach() parameters for iterable declaration is inconsistent with other definitions 2019-02-28 14:28:58 +0000 1 1 1 Unclassified WebAppsWG WebIDL unspecified PC Linux RESOLVED WORKSFORME P2 normal --- 1 ddorwin cam mike Ms2ger public-script-coord watsonm public-webapps-bugzilla oldest_to_newest 122237 0 ddorwin 2015-07-20 20:40:32 +0000 In the forEach section [1], Step 9.3 of the “If the interface has a maplike declaration or setlike declaration...” algorithm says “Call the [[Call]] internal method of callbackFn with thisArg as thisArgument and v, k and object as argumentsList.” This value followed by key ordering is consistent with ES6 Map [2] and Array [3]. However, step 4.2 of the “If the interface has an iterable declaration...” algorithm says to “Invoke callback with thisArg as the callback this value and k and value as its arguments.” This would appear to cause the opposite order of parameters being passed to the callback. Is this intentional? Also, [4] says “If two type parameters are given, then the interface has a pair iterator and provides value pairs, where the first value is a key and the second is the value associated with the key.” Thus, the “value” passed to the interface is [key, value], which is similarly inconsistent. My interpretation of the current text is that forEach() callbacks would receive the following parameters based on the declaration type: * For maplike declarations: (somevalue, somekey) * For iterable declarations with a single type parameter: (index_k, somevalue) * For iterable declarations with two type parameters: (index_k, [somekey, somevalue]) It would seem more consistent (and correct for ECMAScript language binding?) for the callback for iterable’s forEach() to receive the following instead: * For iterable declarations with a single type parameter: (somevalue, index_k) * For iterable declarations with two type parameters: ([somevalue, somekey], index_k). [1] http://heycam.github.io/webidl/#es-forEach [2] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/forEach#Description [3] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach [4] https://heycam.github.io/webidl/#dfn-pair-iterator 126629 1 watsonm 2016-05-31 15:10:41 +0000 It looks like this issue has been solved in the draft at https://heycam.github.io/webidl/#es-forEach. Should this bug be closed ? 126650 2 ddorwin 2016-06-02 19:21:15 +0000 These issues were discussed in https://lists.w3.org/Archives/Public/public-script-coord/2015OctDec/0039.html. For pair iterators, there was agreement to use "value, key, this". I believe the "If the interface has an iterable declaration..." text has been replaced with "If the interface has a pair iterator..." The corresponding algorithm now says, "Invoke callback with thisArg (or undefined, if the argument was not supplied) as the callback this value and value, key and O as its arguments." 129581 3 Ms2ger 2019-02-28 14:28:58 +0000 Current status: * For iterable declarations with a single type parameter (interface defines an indexed property getter): uses Array.prototype.forEach => (value, index, object). * For iterable declarations with two type parameters: (value, key, object). * For maplike declarations: uses Map.prototype.forEach => (value, key, object). * For setlike declarations: uses Set.prototype.forEach => (value, value, object).