If you are already comfortable with jQuery, you may be tempted to skip this section. However, at least take a quick glance because this section covers jQuery from a game-specific angle.
Loading jQuery directly means that you have complete control over the file and the page. This is both a good and a bad thing. jQuery is a large library, and if it’s not served properly (minified and compressed), it can be a beast. jQuery 1.7 clocked in at nearly 250 kb; if served compressed and minified, however, jQuery is only 33 kb. If you are serving it directly off your web server you need to make sure you are serving a minified version with its cache headers set correctly, so the code isn’t sent on subsequent reloads. (See the next chapter for more details on cache headers.)
Another advantage of using a CDN is that most CDNs have edge-locations around the world, meaning wherever in the world your game players are located, they will be near a CDN server location with a fast connection to the Internet. This isn’t something that you can always guarantee when serving files off a standard web server.
One last advantage of using a CDN is that, given the ubiquity of jQuery, there’s a good chance ...