When I saw it, I thought, “That doesn’t look right. It won’t work.” But I was wrong. Sure, it’s missing an ‘http:’ or ‘https:’ prefix, but it works just fine. Look at the source for this page, and you’ll see that there is no ‘http’ or ‘https’ in the link above. But if you click on it, it loads jQuery without any trouble.
Protocolless URLs are interesting, but what’s the point? And what are the other options?
How can you add a script tag that loads jQuery?