jQuery Linking vs. Download?

Question

Which way is better? To link to the jQuery Pack at http://ajax.googleapis.com. Or to download the appropriate file and link locally? Does it matter? Is there a chance the link may disappear? Or is there a chance the file online will be updated, and it's better to link to it? Curious.

Thanks, Tracy

Answer 1

From the Google Code site:

Google works directly with the key stake holders for each library effort and accepts the latest stable versions as they are released. Once we host a release of a given library, we are committed to hosting that release indefinitely.

One of the main points of Google hosting the jQuery library is so that it is cached in a single place. Consider the following scenario:

1. User visits site A
2. Site A has jQuery on the same domain, so the file is downloaded by the browser
3. User visits site B
4. Site B has jQuery on the same domain, so the file is downloaded by the browser a second time.

Now if we all fetched jQuery from the Google servers, the scenario goes like this:

1. User visits site A
2. Site A loads jQuery from Google, so it's downloaded by the browser
3. User visits site B
4. Site B loads jQuery from Google, but the browser already downloaded it and cached it, so fetching the file again is instantaneous.

Answer 2

What if the user comes from a country where Google is banned? Also, some time ago we had to pay for international internet traffic (while regional traffic was "free") in my country an I suspect it may be still the case in some other countries. Users would be upset for having to pay for jQuery. Even minimized. It's safer to keep the files you need on your server.

EDIT: Another reason for not using jQuery from Google servers (if used on your intranet: https://meta.stackexchange.com/questions/10071/employer-blocks-jquery-from-google-doh)