I am experimenting with catching Javascript errors with raven.js [1] (see the JS error logging RfC [2] for background; see T1345 [3] for a prototype for JS error logging). For various reasons, Javascript does not have a reliable way to install a global exception handler like e.g. PHP does with set_exception_handler(), so the standard way of doing this is to wrap modules into a try-catch block.

ResourceLoader already wraps minified scripts with something like

mw.loader.implement( "<module name>", function() { <module code> } );

so this could be changed to something like

mw.loader.implement( "<module name>", Raven.wrap( function() { <module code> } ) );

That means that the error logging module would have to be loaded by the time other modules are initialized, so I imagine it would have to become a startup module. My questions are:

1. do you see any problems with such a setup? The eventual goal would be to use this on the Wikimedia production cluster. 2. especially, is adding another startup script acceptable? (Adding raven.js to the jquery and mediawiki modules would mean a ~10% size increase.) 3. what would be the proper way of doing this from an extension? Add two new hooks for module wrapping and for defining additional startup modules?

[1] https://github.com/getsentry/raven-js [2] https://www.mediawiki.org/wiki/Requests_for_comment/Server-side_Javascript_e... [3] https://phabricator.wikimedia.org/T1345