When I develop iPhone / iPad apps I always use a crash reporting system. My current favorite is Crashlytics - which works great.
For Android apps I've been using the rather more basic ACRA crash reporter.
Now that I'm building a webapp to be run on a client's own server, it seems a good idea to build in some kind of crash reporting system, probably linked off the window.onerror event.
Of course, I could build my own system. But does anyone know a good drop-in solution that sends and collates reports?
Incidentally, I'd prefer a completely client-side solution (i.e. just JavaScript) rather than anything that requires server support.
Both Exceptional and Airbrake offer javascript implementations
Update
Exceptional was officially shut down in favor of Airbrake (Source)