Safari has done it for a long time, Chrome and the others more recently. Even back in 2012 people were raising the question of whether shared caching of librar

Safari has done it for a long time, Chrome and the others more recently. Even back in 2012 people were raising the question of whether shared caching of libraries from the public JS CDNs was effective — due to too many different versions in use, and content being evicted from the browser cache sooner than most expected