Changes from November 8, 2013 Draft Rev 21: > Calling the next method of a completed generator returns a “done” result instead of throwing The reason for this change was to unify the behaviour of completed generator functions compared to array or collection objects iterators. Test case: --- js> function*g(){ } js> o = g(); o.next(); o.next() Expected: IteratorResult object `({value:(void 0), done:true})` Actual: throws TypeError "generator has already finished" ---

Right, this is 25.3.3.2, step 5 for .next() and 25.3.1.3, step 7 for .throw()

Comment on attachment 8358948 [details] [diff] [review] Return IteratorResult object for completed generators instead of throwing Review of attachment 8358948 [details] [diff] [review]: ----------------------------------------------------------------- ::: js/src/jsiter.cpp @@ +1736,5 @@ > + RootedObject obj(cx, CreateItrResultObject(cx, args.get(0), true)); > + if (!obj) > + return false; > + args.rval().setObject(*obj); > + return true; 25.3.1.3, step 7 returns a completion record with [[type]]=throw, not [[type]]=normal. I guess that means using cx->setPendingException()?

> 25.3.1.3, step 7 returns a completion record with [[type]]=throw, not > [[type]]=normal. I guess that means using cx->setPendingException()? Yes it does, thanks! Also, of course the previous behavior was tested extensively, so this version contains various test changes. Try-servering here, in case any chrome code relies on the previous behavior, already: https://tbpl.mozilla.org/?tree=Try&rev=14913d4c2a18

Comment on attachment 8358953 [details] [diff] [review] Return IteratorResult object for completed generators instead of throwing. v2 Review of attachment 8358953 [details] [diff] [review]: ----------------------------------------------------------------- Great. ::: js/src/jsiter.cpp @@ +1707,5 @@ > JSGenerator *gen = thisObj->as<StarGeneratorObject>().getGenerator(); > > if (gen->state == JSGEN_CLOSED) { > + RootedValue val(cx, UndefinedValue()); > + RootedObject obj(cx, CreateItrResultObject(cx, val, true)); You can use UndefinedHandleValue here instead of an extra root. ::: js/src/tests/ecma_6/Generators/delegating-yield-6.js @@ +46,5 @@ > > assertEq(log, "indndndndndndv"); > > // Outer's dead, man. Outer's dead. > +assertDeepEq(outer.next.bind(outer)(), {value: undefined, done: true}); Please change `outer.next.bind(outer)()` to `outer.next()`.

https://developer.mozilla.org/en-US/Firefox/Releases/29/Site_Compatibility This doc is outdated... https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Iterators_and_Generators

Also added to https://developer.mozilla.org/en-US/Firefox/Releases/29#JavaScript and https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/yield#IteratorResult_object_returned_instead_of_throwing https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function*#IteratorResult_object_returned_instead_of_throwing