• I use Firefox 30 on Fedora 20.
• I've set https://en.wikisource.org/wiki/Special:Preferences#mw-prefsection-rendering to "Modern" skin.
• I go to https://en.wikisource.org/wiki/Page:Scheme_-_An_interpreter_for_extended_lambda_calculus.djvu/14

-> No problems.

How do you know that it "runs endlessly"? What's the outcome? Do you want to imply that Firefox creates an "Unresponsive script" error message?

Could you please open the "Web Developer -> Network" Tool and reload the page that you see the problem on? It should display how long a certain script takes.
For more information please see: https://developer.mozilla.org/en-US/docs/Tools/Network_Monitor

Created attachment 15819
Script running

Attached:

The pages which triggered the script messages were as follows:
https://en.wikisource.org/wiki/Page:Popular_Science_Monthly_Volume_21.djvu/886
https://en.wikisource.org/wiki/Page:Popular_Science_Monthly_Volume_21.djvu/887
https://en.wikisource.org/wiki/Page:Popular_Science_Monthly_Volume_21.djvu/888
https://en.wikisource.org/wiki/Page:Popular_Science_Monthly_Volume_21.djvu/889
https://en.wikisource.org/wiki/Page:Popular_Science_Monthly_Volume_21.djvu/890
https://en.wikisource.org/wiki/Page:Popular_Science_Monthly_Volume_21.djvu/891

The editing environment was as follows:

The page was loaded in "Preview mode" so that I could edit an incorrect anchor. Then, with each edit, I re-clicked on Preview for not wanting to constantly use "Save". I considered that this problem relates to the time of the day (high rate of usage according to my ISP).

Today, I tried again on one of the above pages, unfortunately I didn't see the Firefox "Network" stats but I am attaching the screenshot of the event.

Here is an additional comment from another Wikisource user that may be helpful:

https://en.wikisource.org/wiki/Wikisource:Scriptorium/Help#Mediawiki_bug.3F

I am attaching three more images of the script problem, one of which is in the main namespace. When the message appears and "Continue" is clicked, the the browser hangs. If the "Stop script" is clicked, then the message disappears and I can continue working and nothing is lost. I couldn't get the error to kick in while the Network analysis was in view. It's inaccessible when the message pops up.

Created attachment 15830
Script triggered a message

Attached:

Created attachment 15831
Script triggered a message 2

Attached:

Created attachment 15832
Script triggered a message 3

Attached:

I think this and bug 67420 are the same.

ineuw, thanks for the comprehensive report. There's already some more information on bug 67420, so I'm going to dupe this one there.

• This bug has been marked as a duplicate of bug 67420 ***