Don’t Use jquery-latest.js

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Earlier this week the jQuery CDN had an issue that made the jquery-latest.js and jquery-latest.min.js files unavailable for a few hours in some geographical areas. (This wasn’t a problem with the CDN itself, but with the repository that provides files for the CDN.) While we always hope to have 100% uptime, this particular outage emphasized the number of production sites following the antipattern of using this file. So let’s be clear: Don’t use jquery-latest.js on a production site.

We know that jquery-latest.js is abused because of the CDN statistics showing it’s the most popular file. That wouldn’t be the case if it was only being used by developers to make a local copy. The jquery-latest.js and jquery-latest.min.js files were meant to provide a simple way to download the latest released version of jQuery core. Instead, some developers include this version directly in their production sites, exposing users to the risk of a broken site each time a new version of jQuery is released. The team tries to minimize those risks, of course, but the jQuery ecosystem is so large that we can’t possibly check it all before making a new release.

To mitigate the risk of “breaking the web”, the jQuery team decided back in 2013 that jquery-latest.js could not be upgraded to the 2.0 branch even though that is technically the latest version. There would just be too many sites that would mysteriously stop working with older versions of Internet Explorer, and many of those sites may not be maintained today.

As jQuery adoption has continued to grow, even that safeguard seems insufficient to protect against careless use of http://code.jquery.com/jquery-latest.js. So we have decided to stop updating this file, as well as the minified copy, keeping both files at version 1.11.1 forever. The latest released version is always available through either the jQuery core download page or the CDN home page. Developers can download the latest version from one of those pages or reference it in a script tag directly from the jQuery CDN by version number.

The Google CDN team has joined us in this effort to prevent inadvertent web breakage and no longer updates the file at http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.js. That file will stay locked at version 1.11.1 as well. However, note that this file currently has a very short cache time, which means you’re losing the performance benefit of of a long cache time that the CDN provides when you request a full version like 1.11.1 instead.