761236 - InvalidAccessError from cssRules.length

Status: NEW

(Core :: DOM: CSS Object Model, defect)

Description

[Joe Walker [:jwalker]]

Firebug is using CssLogic.jsm to display style information in it's new computed style view, but on page reload is getting the following error:

JavaScript error: resource:///modules/devtools/CssLogic.jsm, line 1042: InvalidAccessError: A parameter or an operation is not supported by the underlying object
The relevant line is basically 'return this.domSheet.cssRules.length;'

This does not appear to be a problem with CssLogic because we can force the error to happen by calling 'cssRules.length' directly from FireBug without touching CssLogic.

It does not appear to be a stale document handle, I've checked that the document being used here is the expected one.

Any help in debugging this problem would be appreciated.

Comment 1

[Boris Zbarsky [:bzbarsky]]

You get NS_ERROR_DOM_INVALID_ACCESS_ERR if you try to read .cssRules on a stylesheet that's not done being parsed yet.  That seems like the most obvious thing to be going on here.

Comment 2

[Sebastian Zartner [:sebo]]

Honza could fix this issue for Firebug at https://github.com/firebug/firebug/commit/e2c65385388ead9639624542d729810433fe506b by waiting for the "load" event to be fired.
Though the highlight() function of CssLogic.jsm should also be fixed to avoid others having the same problems.

Sebastian

Comment 3

[Dennis Schubert [:denschub]]

Not sure if this is still an issue, but the one case where it was broken got fixed by the site. We have not seen new reports for many years, so even if this still exists, it's low priority.