251615 - Trying to dynamically set tabIndex on some elements causes error

Status: RESOLVED FIXED

(Core :: DOM: UI Events & Focus Handling, defect)

Description

[Ryan Frishberg]

User-Agent:       Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8a3) Gecko/20040715

I know tabIndex wasn't really supported before, but atleast when I tried to 
set an element that didn't allow tabIndex, it didn't have any adverse affects 
on the JavaScript.

I think it's related to bug 171366

Reproducible: Always
Steps to Reproduce:
1.  Create a <div>
2.  With JS, try to set the element's tabIndex property
Actual Results:  
You'll get an error in the JS console saying that you were trying to set a 
property that only has a getter and your script will stop running

Expected Results:  
With bug 171366 fixed it should've set and recognized the tabIndex property.  
Otherwise, it should've just ignored it and not produced an error.

It works fine for links and it doens't produce an error in 1.7

Comment 1

[Ryan Frishberg]

Attachment: SHows that tabIndex can be set for links but not for div's

Comment 2

[Ryan Frishberg]

Related to bug 250006

Comment 3

[Aaron Leventhal]

Attachment: I'm an idiot. 1 line patch.

Good catch, thanks for filing this!

Comment 4

[Johnny Stenback (:jst)]

Comment on attachment 153665 [details] [diff] [review]
I'm an idiot. 1 line patch.

r+sr=jst :-)

Comment 5

[Aaron Leventhal]

Checking in nsIDOMNSHTMLElement.idl;
/cvsroot/mozilla/dom/public/idl/html/nsIDOMNSHTMLElement.idl,v  <-- 
nsIDOMNSHTMLElement.idl
new revision: 1.7; previous revision: 1.6
done

Comment 6

[Ryan Frishberg]

Thanks for the quick fix.

I have a quick question, though.  When trying to set a readonly property is it 
really necessary that it be a JS error and stop the rest of the script?  
Couldn't it be just a warning and continue with the processing?

For example, to help cancel events in IE, sometimes I use event.keyCode = 0.  
However, in Mozilla, it returns a JS error: "Error: setting a property that 
has only a getter" and then stops.  It's obviously easy to detect for IE and 
only do that for IE, but I just thought it'd be helpful anyways.

Just my two cents,
Ryan

Comment 7

[Aaron Leventhal]

(In reply to comment #6)
> When trying to set a readonly property is it 
> really necessary that it be a JS error and stop the rest of the script?  

Javascript has a language feature called try/throw/catch. If you wrap things in
try { } and then have the catch statement at the end your script will keep
running through the errors. It's up to you whether to print the javascript
warnings at that point. Look it up in a JS reference. Good luck.

Comment 8

[timeless]

aaronl: that's not precisely accurate, only modern versions of javascript handle
try{} catch(){}. older versions treat them as compiletime errors :) one would
probably want to do <script language="javascript1.3"> or whatever it is that
ensures the browser supports try{}catch(){} before leaping off that cliff...