There are tools like Grunt and WebPack (which depend on Node.js) that can bundle all your dependencies.
I cannot provide details about how they work because I don't do front-end development, but I can tell you about years ago when I had to copy & paste both code and links to jQuery and other libraries like BackBone or Ember.js (relevant at the time) into my projects. Nowadays, web developers seem to prefer the use of tools that came from the Node.js ecosystem to handle these dependencies in a more "engineer-ish" way using NPM packages.