129742 - Hang when going up the offsetParent-path

Status: RESOLVED DUPLICATE of bug 13350

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

Description

[Arthur]

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.8) Gecko/20020204
BuildID:    2002020415

Trying to write my first piece of JavaScript I've hung mozilla: I'm trying to
calculate the absolute position of an element and therefore I'm adding up all
the offsetLeft and offsetTop values belonging to all offsetParents of the
element (I've no idea whether this is the right way to do this). This seems to
hang mozilla with a high CPU load. I've stripped down the testcase a bit.

Reproducible: Always
Steps to Reproduce:
1.Go to the testcase.
2.Move the mouse over the given link


Actual Results:  Mozilla gets irresponsive

Expected Results:  Stay responsive, give me a chance to debug my code :)

Comment 1

[Andrew Schultz]

it's in an infinite loop within findPosY
shouldn't it be:

64     obje = obje.obj.offsetParent

?

you can use the JavaScript debugger to debug this. just set breakpoints before
it hangs in your code, and then step (into) through it.

Comment 2

[Phil Schwartau]

Browser, not engine ---> DOM Level 0

Comment 3

[Phil Schwartau]

I agree with Andrew; this causes an infinite loop in findPosY:

 while (obje.obj.offsetParent)
 {
   curtop += obje.obj.offsetTop;
   obj = obje.obj.offsetParent;
 }

The test condition |obje.obj.offsetParent| is not being altered
in any way inside the loop, so the loop is never going to end...

Similarly for findPosX. Marking Invalid; sorry - 

Comment 4

[Phil Schwartau]

More detail on the above:

In looking through your code, note that the incoming parameter
|obje| has a property called "obj". That is, |obje.obj| is defined.

However, your assignment in the body of the loop says 

              obj = obje.obj.offsetParent;

What you are doing by this is defining a NEW variable |obj|, even
though the |var| keyword has not been used. Thus we now have TWO 
indpendent things: |obje.obj| and |obj|. That is why the assignment
above does nothing to affect the test condition |obje.obj.offsetParent|.

As Andrew suggested, you probably meant to do this instead:

              obje = obje.obj.offsetParent

Comment 5

[Arthur]

Thank's for your help. I duplicate the bug to bug 13350. A hang is after all a
bug. Staying responsive would be very nice in many circumstances.

Comment 6

[Arthur]

Reopening in order to duplicate.

Comment 7

[Arthur]

*** This bug has been marked as a duplicate of 13350 ***