835181 - Array apparently has an undocumented .iterator function (which broke Processing.js)

Status: RESOLVED WORKSFORME

(Core :: JavaScript Engine, defect)

Description

[Pomax]

Apparently there is a new, undocumented, function ".iterator()" on Array in Firefox 17 and up, which is not listed in https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array, and which may cause scripts to break when they try to roll their own.

Processing.js ran into this recently as documented in https://processing-js.lighthouseapp.com/projects/41284-processingjs/tickets/1935-the-for-each-loop-over-arrays-doesnt-work-on-firefox-17#ticket-1935-4 with the fix simply requiring a test to see if Array already had an .iterator()

That said, given that Array already has a .forEach(), the presence of .iterator() might actually be a bug (it could be a native not-supposed-to-be-public function) so I figured I'd file this bug report.

Comment 1

[Jeff Walden [:Waldo]]

This was done intentionally, as I understand it.  If I'd had time to care, I probably would have argued against it some.

jorendorff, this is another reason why having an @@iterator symbol, or whatever, that doesn't pollute the namespace of every object, is better than having a property name that does.

Comment 2

[André Bargull [:anba]]

Array.prototype.iterator was removed some time ago (probably as part of bug 919948) - resolving as WFM.