Also consider adding Silverlight/Moonlight detection to the mix.

I’ve been experimenting with this feature — part of the reason why #355 is taking so long to fix ;) — and I don’t know if it’s that useful of a feature, as it’s very Windows IE-centric.

1) ActiveX objects don’t have a standard method or property for version info. Each plugin is different; each requires plugin-specific code to query the version info, if it exists.

2) For other browsers, navigator.plugins[] doesn’t have a version property; version info is sometimes embedded in the name or description properties…

3) should we collect the version number only? do we detect only genuine plugins or do we include the compatible ones? (eg totem)

The above also adds overhead: more code increases the size of piwik.js and initialization time. (A first party session cookie could be used to avoid plugin version detection on subsequent page visits to this site.)

I think it would be nice to detect Silverlight.
re 3) how would we define “compatible” plugins? It sounds like it may be hard to keep such a list, so I would say “detect only genuine plugin” and “detect only version number”.

Concerning the new feature “detecting the version number”, that would be a nice to have indeed, however it is low priority compared to getting the new piwik.js with the perfect api and tests cases.
Also, this will add a bit of UI complexity: how to display these version numbers? I would suggest that when clicking on the row, eg. “Flash”, it would display a subtable with the version details.

Concerning the overhead added by plugin detection, I would think that the overhead of download/outlink tracking is much bigger especially on pages with 200+ links.
However it would be interesting to profile the whole (new) piwik.js using firebug, on a very complicated page with lots of links, other JS libraries, etc., and also on profile on a very simple page.

I would also love to see the Silverlight’s…

As stated in comment:4, on IE, ActiveX plugin version detection varies between plugins. Meanwhile, on non-IE browsers, version detection has mixed success.

Since we are now proposing to disable ActiveX plugin detection entirely in #852, I am moving the Silverlight detection to a new ticket, #857.