801988 - NaN error in Firefox 16 when trying to call parseInt(null) because old jQuery returned the microdata itemValue (null), not the itemValue attribute

Status: RESOLVED INVALID

(Core :: General, defect)

Description

[Eric Fettman]

User Agent: Mozilla/5.0 (Windows NT 5.1; rv:16.0) Gecko/20100101 Firefox/16.0
Build ID: 20121010144125

Steps to reproduce:

1. Go to http://www.googleanalyticstest.com/setup.aspx?wo=tr
2. Check the Select All Categories checkbox or any of the individual category checkboxes.


Actual results:

In Firefox 16, NaN is showing instead of total questions available.


Expected results:

The number of questions available should appear at the bottom of the page.  (Current total is 225.)  

Analytics for the past week is showing that users with previous versions of Firefox are still getting through this page at the normal rate while no Firefox 16 users are.

Comment 1

[Matthias Versen [:Matti]]

Last good nightly: 2012-06-05
First bad nightly: 2012-06-06

Pushlog:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a7a905fd70d5&tochange=6338a8988917

Comment 2

[Boris Zbarsky [:bzbarsky]]

microdata API landed in that range...

Eric, is this your page?  If so, what script runs when that checkbox is checked?

Comment 3

[Boris Zbarsky [:bzbarsky]]

Oh, nevermind.  What runs is the calculate() function in the main page.  And the problem there is that it does this:

  countSelected += parseInt($(this).parent().attr('itemValue'));

which is best described as "out-of-date jQuery just shot you in the foot".  The problem is that attr() in jQuery 1.4.2 works like so:

  // If applicable, access the attribute via the DOM 0 way
  if ( name in elem && notxml && !special ) {
    // Some special-casing gunk here that doesn't apply in our case
    return elem[ name ];
  }
  // Fall back on getAttribute

And microdata API adds a property called "itemValue" on all elements.  The return value of this property is defined by http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html#dom-itemvalue and in particular the relevant bit is:

  If the element has no itemprop attribute
    The attribute must return null on getting and must throw an InvalidAccessError exception
    on setting.

So the above code calls parseInt(null), which is the same thing as parseInt("null"), which is NaN.  Hence countSelected ends up as NaN.

I just checked the current jQuery version (1.8.2) and it looks like they have fixed attr() to use getAttribute if available, which incidentally makes this page work if that version of jQuery is used.

Comment 4

[Eric Fettman]

Boris (and Matthias), thanks for the quick response.  I'll make sure to upgrade to jQuery 1.8.2.

Comment 5

[Matthias Versen [:Matti]]

Thanks Boris, that saved me from bisecting...

Comment 6

[Eric Fettman]

Just want to confirm that jQuery 1.8.2 took care of the problem (in Firefox 16 and in Opera 11.64 as well).  Thanks again for the very speedy help - I really appreciate it.

Comment 7

[Boris Zbarsky [:bzbarsky]]

Eric, you're very welcome!  Thank you for the bug report.

Marking invalid, assuming the spec on this won't change...