jQuery 3.0: The Next Generations

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It’s hard to believe it’s been nearly eight years since jQuery was released. Web development has changed a lot over the years, and jQuery has changed along with it. Through all of this time, the team has tried to walk the line between maintaining compatibility with code from the past versus supporting the best web development practices of the present.

One of those best practices is semantic versioning, or semver for short. In a practical sense, semver gives developers (and build tools) an idea of the risk involved in moving to a new version of software. Version numbers are in the form of MAJOR.MINOR.PATCH with each of the three components being an integer. In semver, if the MAJOR number changes it indicates there are breaking changes in the API and thus developers need to beware.

The concept of versioning gets a little more nuanced with jQuery, where browser compatibility can be just as important as API compatibility. In order to create a slimmer jQuery, the team started shipping two versions in 2013. The first version remained numbered in the 1.x line and, currently at 1.11.1, maintains compatibility with a maximal number of browsers. The second version, starting with 2.0.0 and now at 2.1.1, dropped support for browsers like IE8 or lower in order to streamline the code. Both the 1.x and 2.x versions of jQuery have the same public APIs, even though they differ somewhat in their internal implementations.

Our next releases will use a different nomenclature. As before, there will be two different released files. The successor to what is now version 1.11.1 will become jQuery Compat 3.0. The successor to jQuery 2.1.1 will be jQuery 3.0. There are two different packages on npm and Bower, but they share the same version to indicate they have the same API behavior.

We’ll also be re-aligning our policy for browser support starting with these releases. The main jQuery package remains small and tight by supporting the evergreen browsers (the current and previous versions of a specific browser) that are common at the time of its release. We may support additional browsers in this package based on market share. The jQuery Compat package offers much wider browser support, but at the expense of a larger file size and potentially lower performance.

Despite the big version number jump, we don’t anticipate a lot of migration issues for most current jQuery code. We’re just being good semver citizens with this version bump. Changes such as removing deprecated methods will be detected by a new version of the jQuery Migrate plugin to make them easy to find and fix. We’ll have more details on the changes in future blog posts.

So, here’s the TL;DR for version 3.0 of the jQuery API:

If you need support for the widest variety of browsers including IE8, Opera 12, Safari 5, and the like, use the jQuery-Compat 3.0.0 package. We recommend this version for most web sites, since it provides the best compatibility for all website visitors.

If your web site is built only for evergreen leading-edge browsers, or is an HTML-based app contained in a webview (for example PhoneGap or Cordova) where you know which browser engines are in use, go for the jQuery 3.0.0 package.

Until we announce otherwise, both packages will contain the same public APIs in correspondingly-numbered major and minor versions. This should make it easy for developers to switch between the two and be maximally compatible with third-party jQuery plugins.

With each future release, we’ll be making both packages available on npm and bower. Both packages will also be available as single-file builds on the jQuery CDN. Using them from there is as simple as including either jquery-compat-3.0.0.js or jquery-3.0.0.js depending on your needs. We’ve talked with the folks who run Google’s CDN and they will also be supporting both packages.

As we make further progress on version 3.0, we will update everyone with the details about code changes, supported browsers, and the like. Stay tuned!