937348 - Blob constructor does not accept non-Array blob parts

Status: RESOLVED INVALID

(Core :: General, defect)

Description

[Victor Costan]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:25.0) Gecko/20100101 Firefox/25.0 (Beta/Release)
Build ID: 20131030203622

Steps to reproduce:

1. Call the Blob constructor with a sequence object.

Test case: http://jsbin.com/alEMuQu/1


Actual results:

The constructor throws an exception.


Expected results:

The constructor should return a Blob.
http://www.w3.org/TR/FileAPI/#dfn-Blob

Comment 1

[Victor Costan]

This bug was recently fixed in Chrome: http://crbug.com/314755

Comment 2

[Boris Zbarsky [:bzbarsky]]

Fwiw, there is a proposal right now that this testcase should in fact not work, since this is not an iterable object.  See https://www.w3.org/Bugs/Public/show_bug.cgi?id=23683

That said, if nothing else changes it'll start working once Blob is switched to WebIDL bindings.

Comment 3

[Victor Costan]

Thank you!

Please let me know if something changes, and I'll update the Blink and WebKit code to implement what the spec ends up mandating.

Comment 4

[Anne (:annevk)]

Not sure why I'm needsinfo'd, but yeah, I think the plan still is to only allow iterables.

Comment 5

[Boris Zbarsky [:bzbarsky]]

You were needinfo'd because this is an example of people in the wild using non-iterables with sequence, which browsers are working on supporting.  So if we're going to change how sequence behaves, we better do it asap....

Comment 6

[Boris Zbarsky [:bzbarsky]]

Victor, consensus seems to be that sequence should take iterables; I will be working on implementing that in Gecko.  It would be good to not ship something different in Chrome...

Comment 7

[Victor Costan]

Thank you, Boris!

So, until the meaning of iterable is spec'd, should I remove the support for objects with length+index properties? Is there anything else/better I can do?

Comment 8

[Boris Zbarsky [:bzbarsky]]

My current plan is to define "iterable" as "an object and GetProperty(obj, @@iterator) returns a callable object", I think.  The discussion on exactly how this should work died down.  :(

Note that in Gecko DOM nodelists are iterable in this sense, as are arrays and String objects...

Comment 9

[Boris Zbarsky [:bzbarsky]]

I filed bug 952890 to track implementing sequences as iterables.

Comment 10

[Victor Costan]

Thank you for pointing me to it, Boris! I'll try to find some time soon to investigate matching what you're doing in Blink and WebKit.

Comment 11

[Petruta Horea [:phorea], Desktop Test Engineering (back on Sep 5th)]

Mozilla/5.0 (X11; Linux x86_64; rv:29.0) Gecko/20100101 Firefox/29.0
The result in latest Nightly build (20140109030203) is "FAIL! The method parameter is missing or invalid."
Marking New as per above comments and bug 952890.

Comment 12

[Boris Zbarsky [:bzbarsky]]

The point is, this isn't supposed to work.