console error for "Got a removal of an actor we didn't know about: server1.conn0.child1/domnode1489" at inspector.js:786, when unticking ::after 'content' declaration in devtools, at Facebook

NEW
Unassigned

Status

()

Firefox
Developer Tools: Inspector
P2
normal
4 months ago
2 months ago

People

(Reporter: dholbert, Unassigned)

Tracking

unspecified
Points:
---

Firefox Tracking Flags

(firefox57 fix-optional)

Details

(I'm starting with a fresh profile)

STR:
 1. Log in to Facebook.

 2. View your main timeline page ( https://www.facebook.com/ )

 3. Inspect a particular tiny element in Devtools -- specifically, the triangle pointer for the text bubble underneath "Create a post" at the top.  (For me, this triangle is a pseudo-element for an element that looks like this:
    <span class="_4-h8"></span>)

 4. In DevTools' DOM inspector view, toggle that ^^ span to open it up and show its pseudo-element ::after child.

 5. Click that psuedo-element ::after child, and click "Rules" on the right.

 6. Untick and retick the checkbox for this declaration several times:
       content: '';

 7. Open the Browser Console (or look at the terminal where you started Firefox from)

 8. Repeat steps 6-7 more times if you like.

ACTUAL RESULTS: Nothing goes wrong the first time I untick/retick the "content" property's checkbox, but from the second time onwards, each untick operation produces an error like this in the browser console (and on my terminal):

> Got a removal of an actor we didn't know about: server1.conn0.child1/domnode1489  inspector.js:786

This error links to the following line of source:
https://dxr.mozilla.org/mozilla-central/rev/8486950bd91878bf077a9ac33cb3c018288fe518/devtools/shared/fronts/inspector.js#786

EXPECTED RESULTS: No such error.



(I tried to create a reduced testcase with just an ::after pseudo-element and a 'content' property, but I couldn't reproduce with that simple testcase. I can reproduce very reliably at Facebook, though. So there's some extra complexity involved with the Facebook site that is required to trigger this bug.)
(In reply to Daniel Holbert [:dholbert] from comment #0)
>  3. Inspect a particular tiny element in Devtools -- specifically, the
> triangle pointer for the text bubble underneath "Create a post" at the top. 
> (For me, this triangle is a pseudo-element for an element that looks like
> this:
>     <span class="_4-h8"></span>)


The triangle element in question is shown in this screenshot (it's just to the lower-right of the "e" at the end of "Create"):
https://bug1380897.bmoattachments.org/attachment.cgi?id=8886443

Updated

4 months ago
Component: Developer Tools → Developer Tools: Inspector

Updated

2 months ago
status-firefox57: --- → fix-optional
Priority: -- → P2
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