Should I link to Google API's cloud for JS lib

Question

I'm looking for the pros/cons of pulling jQuery & other JS libraries from Google API's cloud as opposed to downloading files and deploying directly.

What say you?

---

My decision

The likelihood of the lib already cached on the users system is the overriding factor for me, so I'm going with a permalink to googleapis.com (e.g. ajax.googleapis.com/ajax/libs/…). I agree with others here that loss of access to the Google server cloud is a minimal concern.

Answer 1

In addition to points made by others I'll point out two additional cons:

• An additional external HTTP request, so assuming you have a Javascript file of your own (almost certain) that's two minimum instead of one minimum; and
• IMHO because jQuery load is async your entire page can load before the library has loaded so the effects that you do on document ready are sometimes visibly noticeable to the user when they are applied. I think this is not a great user experience.

Answer 2

I think what would be cool to do is run A/B tests and see what the latency is to load minified version of jquery from Google's servers vs your server. Hopefully that'll put things into perspective. Chances are the Google server might be faster, but in terms of accepting responsibility of down time, nothing beats hosting it yourself.

Answer 3

Con:

• When afraid of DNS poisoning, or when afraid that some public wireless network might not be trusted, then the non-SSL versions might actually not be served by Google at all, opening up drive-by installation of malware. (But: caching is set to be a full year, so even though many browsers will issue a If-Modified-Since request for cached content when hitting refresh, this might still be a theoretical issue as most users will already have cached the resources while using another network.)

• When taking extreme care for your visitors' privacy, you might not want Google to record visits to your site by using their CDN. (Quite theoretical as well, as the same note on caching applies.)