492925 - MediaList[i] reports undefined, not the value from .item(i)

Status: RESOLVED FIXED

(Core :: DOM: CSS Object Model, defect)

Description

[Kevin Decker]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b4) Gecko/20090423 Firefox/3.5b4
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b4) Gecko/20090423 Firefox/3.5b4

The MediaList array accessor API always returns undefined when valid indexes are passed.

I'm not sure where this lies in the spec, but it was unexpected for me as other FF objects that define the item() accessor in the spec also define an array accessor. This is more of a consistency item rather than a strict spec compliance issue.

Reproducible: Always

Steps to Reproduce:
See the referenced page.

      for (var i = 0; i < rule.media.length; i++) {
        out.push(i + ": " + rule.media[i]);
      }

      for (var i = 0; i < rule.media.length; i++) {
        out.push(i + ": " + rule.media.item(i));
      }


Actual Results:  
media[i] returns undefined
media.item(i) returns correct value

Expected Results:  
media[i] === media.item(i) for all i

Tested under 3.5b4 and 3.0.10

Comment 1

[Nickolay_Ponomarev]

Confirmed with Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.3a5pre) Gecko/20100418 Minefield/3.7a5pre. Thanks for the testcase! It would probably be best if you attached it here using 'Add an attachment' link on this page, since the testcases have the tendency to disappear after some time from external sites...

Comment 2

[Boris Zbarsky [:bzbarsky]]

Attachment: Testcase

Comment 3

[Boris Zbarsky [:bzbarsky]]

Attachment: Fix

Kevin, nice catch!  Looks like the code to make all this work has been around for years, but never actually got run....

Comment 4

[Boris Zbarsky [:bzbarsky]]

Pushed http://hg.mozilla.org/mozilla-central/rev/302e3ead2b3e