The versioning system they devised is a very clever way to always serve you the most up-to-date script. For example, you request version 2 of SWFObject and it’ll currently deliver 2.2, but in the future you’ll always get the most recent 2.x release.
I did a bit of research on how they handle these cases, and since these facts aren’t elsewhere, they needed a home. :)
The current caching rules are as follows:
|Request||Response cached for|
jQuery URLs used only for illustration purposes. It’s the same case with all scripts’ minor/major versions Minified and unminified files are treated the same
Previous to now, using the
google.load('jquery','1.2.6') technique was the only way to ensure the script stayed considerably cached. Direct path-based access scripts were only cached for one day. But no worries, because all is better now.