250012 - JavaScript incorrect behaviour with OBJECT tag

Status: RESOLVED INVALID

(Core :: DOM: Core & HTML, defect)

Description

[Vlad Alexander]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040626 Firefox/0.9.1
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040626 Firefox/0.9.1

There seems to be no way using JavaScript to determine if the browser is using
the OBJECT tag or alternate content. For example, using this construct, if the
browser does not find the object clsid, a textarea is rendered:

<object classid="clsid:abc..." id="object1" width="100%" height="400">
     <textarea name="alternate1" id="alternate1" cols="60" rows="15"></textarea>
</object>

However, in Mozilla/FireFox, it is impossible to determine this
programmatically. In IE, the following script works but fails in Mozilla/FireFox.

if (document.getElementById('object1') && document.getElementById('object1') !=
null) {
     alert('object is rendered');
} else {
     alert('textarea is rendered');
}


Reproducible: Always
Steps to Reproduce:
1. create an <object> tag with an invalid clsid
2. use JavaScript to test the existence of this <object>. For example:
alert(document.getElementById('object1'));


Actual Results:  
JavaScript returns an instance of the object even if the object is not rendered.

Expected Results:  
JavaScript should return "null".

Comment 1

[Bill Mason]

*** Bug 250016 has been marked as a duplicate of this bug. ***

Comment 2

[Bill Mason]

*** Bug 250013 has been marked as a duplicate of this bug. ***

Comment 3

[Zibi Braniecki [:zbraniecki][:gandalf]]

Could You provide testcase?

Comment 4

[WADA:World Anti-bad-Duping Agency]

Your condition check is aparantly NOT usability check of <OBJECT> element, is 
existency check of <OBJECT> element ID'ed as "object1".

> if (document.getElementById('object1') && document.getElementById('object1') !=
null)

(1) Left document.getElementById('object1')
    => Returns DOM object for <object id="object1"> element
(2) Right document.getElementById('object1')
    => Returns DOM object for <object id="object1"> element
(3) document.getElementById('object1') && document.getElementById('object1')
    => Returns "right one" since "left one" is not converted to false
    => DOM object for <object id="object1"> is returned

See
http://devedge.netscape.com/library/manuals/2000/javascript/1.5/reference/ops.html#1044813
> &&   expr1 && expr2
> (Logical AND) Returns expr1 if it can be converted to false;
> otherwise, returns expr2. Thus, when used with Boolean values,
> && returns true if both operands are true; otherwise, returns false.

(4) if( document.getElementById('object1')&&document.getElementById('object1') )
    => Returns "true" since DOM object for <object id="object1"> exists
(5) if( conditions ) != null
    => Returns "true" since "true" is aparantly not "null"

I guess that IE has different DOM/JavaScript implementation.
 - When element of <object> tag is not usable due to invalid clsid or  
   something else, JSCRIPT of IE returns null object for <object> element.
(Please note that IE is not W3C complient.)
Can you check the object data on both IE and Firefox?
 var obj = document.getElementById('object1');
 alert((typeof obj)); alert(obj); alert(obj.nodeType); alert(obj.nodeName); etc.
How about when obj is "alternate1"?

Anyway, I believe this bug is INVALID.

Comment 5

[WADA:World Anti-bad-Duping Agency]

Correction on (4) and (5)

(4 & 5) if ( object-returned-at-step3 !=null )
    "true" since DOM object for <OBJECT ID='object1'> exists and is not "null".
    (This can not be null object.)

Comment 6

[Vlad Alexander]

Attachment: Test case for using JavaScript to test non-rendered object tag

In IE, non-existent tags and non-rendered object tags return "null".

Comment 7

[WADA:World Anti-bad-Duping Agency]

(In reply to comment #6)
Opera 7.51 returns [object HTMLObjectElement] for non-rendered object tag in
attachment 152605 [details] as Mozilla does.
This is true when "Identify as" is Opera, Mozilla family, and even when
"Identify as MSIE 6.0".

Comment 8

[Boris Zbarsky [:bzbarsky]]

The HTML and DOM specs _require_ that the <object> actually be present in the
DOM in this case.  Its display behavior (not painting) does not affect its
existence in the document.

Marking invalid.  The current behavior is correct.

Comment 9

[Hixie (not reading bugmail)]

IE doesn't always return null, either. It's very unreliable, in fact.