Manual:$wgVersion/en

Details
The current version of MediaWiki (e.g, ""). You shouldn't need to set this option; it is used internally.

Example code
If you're implementing a new feature that only works in MediaWiki 1.19 or later, but you want to maintain backwards compatibility, you could use a test such as the following:

However, it is typically recommended that you use feature detection to see whether the method or class you wish to use is available instead of depending upon raw version strings.