As per the following links, cross-browser methods to process unhandled exceptions, such as catching them, and getting details such as a call stack.

The common reason is to detect client-side bugs and post them to a server for logging, as an aid to debugging issues only seen 'in the wild'.

http://web.archive.org/web/20100813232637/http://blog.yoursway.com/2009/07/3-painful-ways-to-obtain-stack-trace-in.html

http://web.archive.org/web/20100527065045/http://gist.github.com/156138

Would really appreciate this in the 1.x branch so can use with corporate/intranet clients still using IE8.