This feature is quite an interesting technical feat, considering that it shouldn't really be possible to get error information form 3rd party scripts. See [this](https://github.com/loggly/loggly-jslogger/issues/22) and [this](https://github.com/logentries/le_js/issues/51) for discussions.
Ranked in these QuestionsQuestion Ranking
Pro Generous free plan
Free plan allows for up to 5000 events/month, customizable rate limits, integrations (e.g. with Slack), multiple users, and 30 day retention.
Pro Integrates with Slack
Rollbar can be integrated with Slack to send notifications of various event to a set Slack channel based on customizable rules.
Pro Stack traces (traceback)
Stack trace with function calls and line numbers.
Pro Client library is open source
Pro Custom error grouping
Pro Capture any uncaught errors
Rollbar allows sending any log messages to Rollbar not just exceptions enabling you to go back and check for missed exceptions.
Pro Supports "deploy" events
You can easily send "deploy" events with
curl, so that you know to which version the errors apply. Errors are grouped automatically by name/type, but if the re-occur after a deploy, they'll be shown again above the deploy in the timeline.
Pro Multiple integration options
Asana - Create and resolve Asana tasks
Bitbucket Issues - Create and manage Bitbucket Issues
Campfire - Get alerts in your Campfire room
Flowdock - Get messages in your flow
GitHub Issues - Create and manage GitHub Issues
HipChat - Get alerts in your HipChat room
JIRA - Create, resolve, and reopen JIRA issues
PagerDuty - Trigger and resolve incidents in PagerDuty
Pivotal Tracker - Create and manage Pivotal Tracker stories
Slack - get alerts in a chatroom or group
Sprintly - Create and manage Sprintly items
Trello - Create and manage cards in Trello
VictorOps - Trigger and recover alerts in VictorOps
Webhook - Post JSON payloads to arbitrary URLs
Email - get notifications and daily summaries
Pro Source maps support
Source map support is used to reference original source code in cases where the code is minified.
Pro Error filtering
Rollbar allows ignoring specific exceptions simply by adding the error message to the ignoredMessages array.
Pro Integrates with your existing server-side logging package
Not a hosted option, so you'll store client-side logs along with your server-side logs.
Pro Stack traces
JSNLog passes exception log messages with its stack trace.
Con No context for some errors
Con Old-school UI
Built with the default Bootstrap theme. Looks like 2011.
Con No hosted option
You'll have to store client-side logs along with your server-side logs.
Con No reporting capabilities
Your server logging solution should provide that, and JSNlog integrates with Elmah, Log4Net, NLog, Serilog, Common.Logging.