879807 - Since release 21 FireFox does not show DHTML-Menu

Status: RESOLVED FIXED

(Tech Evangelism Graveyard :: German, defect)

Description

[Frank Weichert]

Attachment: FireFox21-SHTML.html

User Agent: Mozilla/5.0 (Windows NT 5.1; rv:20.0) Gecko/20100101 Firefox/20.0 (Beta/Release)
Build ID: 20130409194949

Steps to reproduce:

Update to release 21


Actual results:

DHTML-Menu is not shown. All older releases working fine.
Example-HTML-File is attacht.


Expected results:

it should work again

Comment 1

[Loic]

Web console:
[18:34:38,999] TypeError: this[i] is undefined @ https://bug879807.bugzilla.mozilla.org/attachment.cgi?id=758611:260

Maybe a dupe.

Comment 2

[Alice0775 White]

Regression window(m-c)
Good:
http://hg.mozilla.org/mozilla-central/rev/e9f39220b8e7
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20130123 Firefox/21.0 ID:20130123031657
Bad:
http://hg.mozilla.org/mozilla-central/rev/35e0c12f4332
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20130123 Firefox/21.0 ID:20130123081412
Pushlog:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=e9f39220b8e7&tochange=35e0c12f4332


Regression window(m-i)
Good:
http://hg.mozilla.org/integration/mozilla-inbound/rev/4d567ebd2624
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20130122 Firefox/21.0 ID:20130122115532
Bad:
http://hg.mozilla.org/integration/mozilla-inbound/rev/059c7e8541e2
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20130122 Firefox/21.0 ID:20130122123031
Pushlog:
http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=4d567ebd2624&tochange=059c7e8541e2

Regressed by:
059c7e8541e2	Boris Zbarsky — Bug 828787. Stop allowing indexed expandos on windows. r=peterv

Comment 3

[Boris Zbarsky [:bzbarsky]]

The new behavior is following the spec, so unless this is happening on a site that can't get changed and is widely used I think the right solution is to fix the site to follow the spec too...

Comment 4

[Tom S [:evilpie]]

A small tip would be to use strict mode [1], which would have cought this bug.
1: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions_and_function_scope/Strict_mode

Comment 5

[Alex Keybl [:akeybl]]

(In reply to Boris Zbarsky (:bz) from comment #3)
> The new behavior is following the spec, so unless this is happening on a
> site that can't get changed and is widely used I think the right solution is
> to fix the site to follow the spec too...

Sounds good - not tracking until we know of major web properties being impacted.

Comment 6

[Frank Weichert]

Ok, I can change the code of my page. But which line is unsupported now?
The Error-Box (german: Fehlerkonsole) does not show any error.
What has been changed in the spec?
I have no idea how to fix it.

Comment 7

[Kohei Yoshino [:kohei]]

Replace

> this[i]=new Image()
> this[i].src=arguments[i]

with 

> (new Image()).src=arguments[i]

Comment 8

[Kohei Yoshino [:kohei]]

This change has been described in the compatibility document.
https://developer.mozilla.org/en-US/docs/Site_Compatibility_for_Firefox_21

You cannot the "this" keyword in the preLoadBackgrounds() because it's the window object. You can use another variable name instead:

> function preLoadBackgrounds(){
>   var img
>   for(i=0;i<arguments.length;i++){
>     img[i]=new Image()
>     img[i].src=arguments[i]
>   }
>   return img
> }

Comment 9

[Boris Zbarsky [:bzbarsky]]

You'd need |var img = []| or something.

But yes, the upshot is that setting window[0] is now ignored (or throws, in strict mode) and in preLoadBackgrounds "this" is "window" because the function is not in strict mode.

Comment 10

[Frank Weichert]

Now my page works again with FireFox release 21.

function preLoadBackgrounds(){
   var img = [];
   for(i=0;i<arguments.length;i++){
     img[i]=new Image();
     img[i].src=arguments[i];
   }
   return img
}

Many Thanks to all.

Comment 11

[Frank Wein [:mcsmurf]]

According to Comment 10 this bug can be resolved as fixed.