I have run into a similar issue when visiting https://scratch.mit.edu/

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Saturday, May 9, 2020 8:59 AM, sagdanoha <[email protected]> wrote:

> In short, on some sites in certain circumstances (details below), LibreJS 
> enters
> an infinite loop which blocks the browser from loading anything whatsoever on
> any page, including newly opened pages, until the browser is killed. While I
> would expect LibreJS's script blocking to break some sites, I don't expect
> it's script blocking to ever block all loading of all parts of all webpages.
>
> If LibreJS is disabled, then these issues immediately vanish. Additionally, I
> tested blocking scripts with the NoScript plugin instead and I could not cause
> any such issue no matter what combination of scripts I tried blocking or
> unblocking. For this reason, I believe the core issue is something in LibreJS 
> as
> opposed to bad configurations with the sites themselves.
>
> The simplest way I've found to reproduce the issue is to do a clean install of
> GNU IceCat 60.7.0 and visit https://lichess.org/ to promptly trigger an 
> infinite
> loop that freezes the browser. I've reproduced the issue with LibreJS 7.20.2 
> and
> seemingly any version of IceCat since at least version 60, though earlier
> versions may have the issue as well. I've also verified that the issue is
> present when LibreJS is installed as a plugin to the latest version of Firefox
> (version 76.0).
>
> I suggest testing with Lichess's website since so far, it's the only site I've
> found that reproduces the issue with 100% consistency. Additionally, Lichess 
> is
> known to be open source under the GNU AGPL 3.0, so in theory there should be 
> no
> risk of running non-free JavaScript while testing.
>
> I have also seen this issue occur on sites other than Lichess however. For
> example, I have occasionally run into this issue when performing a search
> through the URL bar with DuckDuckGo as the search engine. I don't recommend
> trying to reproduce the issue that way though both because that happens far 
> more
> rarely and because it may cause you to run non-free JavaScript while debugging
> the issue.

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