One advantage of a service like CDNJS for a resource used by a number of unique sites, like jQuery, is that the resource will often be in the browser's cache. T

One advantage of a service like CDNJS for a resource used by a number of unique sites, like jQuery, is that the resource will often be in the browser's cache. That value diminishes quickly if the particular version of the resource and the location from which it is served is not widely used. So, for widely used resources like jQuery, it can still make sense even in an HTTP/2 world to use a third party service. On the other hand, other HTTP/1.1 performance techniques, like domain sharding, can actually substantially hurt HTTP/2 performance.