Use a CDN
Remember, you can always use the CDN for your very familiar and shared libraries. (I think about this a lot.) And of course, if your CDN fails, you can always fall back locally. But when you do this, you’re generating another HTTP call which can slow down your site, right? I used to be somewhat against this idea, but with the proliferation of sites using the shared CDNs, we don’t actually have to issue that next HTTP. A lot of your visitors might actually have this cached right on their system now and don’t need to make that round trip.
user.js file that has all logged in functions instead.