669926 - alerts break the single JavaScript thread, messing up setTimeout

Status: RESOLVED DUPLICATE of bug 637264

(Firefox :: General, defect)

Description

[cjavapro]

User Agent: Mozilla/5.0 (Windows NT 6.0) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.112 Safari/534.30

Steps to reproduce:

Run this simple htm page
<script>
var failsafe = setTimeout(function () {
    alert('JavaScript Error')
}, 1)
alert('1')
alert('2')
clearTimeout(failsafe)
</script>


Actual results:

Alerted
1
JavaScript Error
2


Expected results:

alert 1 2 and don't alert X

I have used this as a way to detect an error. So if some code threw an error, clearTimeout would never be called. But with this new version of Firefox, some of my pages show JavaScript Error, even if there is no error.

This may or may not be the same bug as https://bugzilla.mozilla.org/show_bug.cgi?id=637264

Also, this was recreated by replacing the two alerts 1 and 2 with a call to window.open. That may not be the same issue. Lets fix this one first.

Comment 1

[Thomas Ahlblom]

Reproduced:
Mozilla/5.0 (X11; Linux x86_64; rv:5.0) Gecko/20100101 Firefox/5.0

Works for me:
Mozilla/5.0 (X11; Linux x86_64; rv:6.0a2) Gecko/20110705 Firefox/6.0a2
Mozilla/5.0 (X11; Linux x86_64; rv:8.0a1) Gecko/20110707 Firefox/8.0a1

Comment 2

[cjavapro]

I forgot to mention that this is intermittent. Does not always happen, but seems to happen more than half the time in my Firefox 4.0 for Ubuntu. Cannot recreate in Windows Vista Firefox 3.6.18

Comment 3

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Yes, this is one of the observable consequences of Bug 637264.