Many javascript errors on production sites go unnoticed: they’re only ever visible to the visitor and never tracked – what a wasted opportunity!

This script catches any client-side errors that occur in any modern browser and pass the information – line number, URL, stack trace – to the server for logging. It can provide significant insight into problems occurring on your web sites and applications that otherwise would go missed.

https://github.com/benkeen/js-error-logs