On 3/6/14 3:58 PM, Domenic Denicola wrote:
>> That would not allow us to kill DOMStringList.
>
> Can we get more background on DOMStringList?

Sure.  It's used in the following places in Gecko, as far as I can tell:

1) document.styleSheetSets.
2) Microdata API.
3) Various places in indexeddb.
4) The DataTransfer API.
5) Some sort of offline resource list API that's not part of any 
standard I can find.

#1 is not implemented by anyone but Gecko, and the spec is claiming it's 
a DOMString[], which no on implements at all.

#2 is likewise not implemented by anyone but Gecko at this point, and 
the spec likewise claims DOMString[] (which again no one implements).

For #3 I've heard Jonas claim he'd like to just moving ES arrays there.

#4 is specced as a DOMString[], which again no one implements.

I don't know offhand what other UAs do for #3 and #4.

> It seems unlikely that you could get away with replacing a string-only type, which, from the specs I can find, seems to be immutable and have an additional index() method

DOMStringList in Gecko does not have an index() method.  Did you mean 
item()?

Whether it's OK to replace with a mutable and any-type-containing thing 
is an interesting philosophical question.  Some of the above use cases 
may be OK with using a frozen array, for example, or not care if the 
page changes it around, since the browser doesn't plan to use it itself.

But yes, it's not a priori obvious that one can replace the other.

> https://developer.mozilla.org/en-US/docs/Web/API/DOMStringList implies it's not implemented in Mozilla

That page was a bald-faced lie.  Note the "in need of a technical 
review" bit.  ;)  I've removed the completely bogus part for now.

-Boris

On 3/6/14 3:58 PM, Domenic Denicola wrote:
> Can we get more background on DOMStringList?

Sure.  It's used in the following places in Gecko, as far as I can tell:

1. `document.styleSheetSets`.
2. Microdata API.
3. Various places in indexeddb.
4. The DataTransfer API.
5. Some sort of offline resource list API that's not part of any standard I can find.

\#1 is not implemented by anyone but Gecko, and the spec is claiming it's 
a DOMString[], which no on implements at all.

\#2 is likewise not implemented by anyone but Gecko at this point, and 
the spec likewise claims DOMString[] (which again no one implements).

For #3 I've heard Jonas claim he'd like to just moving ES arrays there.

\#4 is specced as a DOMString[], which again no one implements.

I don't know offhand what other UAs do for #3 and #4.

> It seems unlikely that you could get away with replacing a string-only type, which, from the specs I can find, seems to be immutable and have an additional index() method

DOMStringList in Gecko does not have an index() method.  Did you mean 
item()?

Whether it's OK to replace with a mutable and any-type-containing thing 
is an interesting philosophical question.  Some of the above use cases 
may be OK with using a frozen array, for example, or not care if the 
page changes it around, since the browser doesn't plan to use it itself.

But yes, it's not a priori obvious that one can replace the other.

> https://developer.mozilla.org/en-US/docs/Web/API/DOMStringList implies it's not implemented in Mozilla

That page was a bald-faced lie.  Note the "in need of a technical 
review" bit.  ;)  I've removed the completely bogus part for now.