FireFox has stopped showing JS

Question

Last night, I was trying to debug a particular bit of vanilla JavaScript on a private page. After a half an hour or so, the browser crashed while in the middle of stepping through a troublesome section. When FireFox restarted, FireBug insisted that there was no JavaScript on the page - does anyone have any ideas what is causing this? Clearly the JS was (nearly) valid before the crash, and wasn't changed before I restarted. The only thing I can see, is that FireBug probably installed an update at that point?

I've tried cutting out all of my code, but nothing seems to make a difference. Other pages, even on the same intranet site, still work, but this one doesn't list any files under the "Script" drop down.

I've compared with the built-in Dev tools, and they also show no JavaScript loaded. The JS is a form submission handler, and clearly it is no longer running when the form is submitted.

Answer 1

I struggled with this for much of today. Eventually resolved it by creating a new profile.

I would be very interested in learning of the root cause if anyone figures it out.