Bug 33510 – selection.modify() should throw an exception if the selection does not have a range or is detached

• Component: HTML Editing
• Status: RESOLVED WONTFIX

[Justin Lebar]

If we call selection.removeAllRanges() or selection.getRangeAt(0).detach(), then perhaps selection.modify() should throw an exception, indicating that there's no selection to modify.  selection.modify() currently silently fails in this case.

[Mats Palmgren]

DOMException INVALID_STATE_ERR is used in HTML5 Selection
when there's something wrong with the selection range:
http://www.whatwg.org/specs/web-apps/current-work/#selection-0

and in DOM-Level-2-Traversal-Range when using a detached range:
http://www.w3.org/TR/DOM-Level-2-Traversal-Range/ranges.html#Level-2-Range-idl

so INVALID_STATE_ERR seems like the appropriate exception to use here.

[Alexey Proskuryakov]

I don't think we should do that. There is a significant chance that raising an exception where we didn't do that previously will break some pages - and the potential benefit is extremely minor.

[Ryosuke Niwa]

I agree with Alexey.  Throwing an exception at this point will break existing web pages.  Does Firefox 4 throws an exception in such cases?

[Hajime Morrita]

FYI, Bug 33509 had similar discussion and concludes not to throw an exception.

[Ryosuke Niwa]

(In reply to comment #4)
> FYI, Bug 33509 had similar discussion and concludes not to throw an exception.

Ok.  We should close these bugs as invalid.

[Ryosuke Niwa]

Oops, I meant wontfix.

[Justin Lebar]

(In reply to comment #3)
> I agree with Alexey.  Throwing an exception at this point will break existing web pages.  Does Firefox 4 throws an exception in such cases?

We silently fail.  +1 on the WONTFIX.