Copying gives you stability. I work in a regulated environment so every change has to be scrutinized. Updating  a library like jQuery is a big deal. If you use 10 libraries of decent size you will most likely rarely update them because it&#x27;s too much work and risk.<p>By isolating out parts you actually need you have a better chance of making updates with reasonable effort.<p>Not saying this is for everybody but a lot of dependencies can be a killer.