The developers behind the popular jQuery JavaScript library recently published a blog entry with details about the project’s development roadmap. In the note, they announced plans to drop support for legacy versions of Microsoft’s Internet Explorer Web browser in jQuery 2.0

The 2.0 update is expected to release next year. Web developers need not worry, however, because the jQuery team has a plan to ensure that old versions of IE are still supported. A separate 1.9 release to be issued in parallel will leave legacy IE support intact.

The jQuery library is extremely popular among Web developers and is used on some of the largest sites on the Internet. It provides a number of convenience methods and utility functions that dramatically simplify DOM manipulation and other tasks that are common in modern Web applications.

There are a large number of third-party plugins and other frameworks that are built on top of jQuery’s core functionality, including an HTML user interface library and a mobile Web development framework. The jQuery library is dual-licensed, available under the terms of GNU’s General Public License or the MIT license.

Version 1.8, an update that will include an overhauled CSS selector engine and other improvements, is currently in beta and is expected to release soon. After the 1.8 release, the developers will turn their attention to the major overhaul that is in the works for 2013. They want to make jQuery lighter, faster, and more modular. But the limitations and deficiencies in legacy versions of Internet Explorer are preventing them from meeting their goals.

In order to move the library forward and improve the quality of the implementation, they have decided to eschew support for Internet Explorer 6, 7, and 8 in jQuery 2.0. That will allow them to streamline the library and drop a lot of the workarounds and special case code that is needed to support old versions of IE.

But the developers are also taking steps to accommodate the statistically non-trivial number of users that still run outdated versions of Internet Explorer. Their plan is to issue a jQuery 1.9 release in parallel with 2.0. The 1.9 series will offer full API compatibility with 2.0 (to the extent that they will be largely interchangeable) but it will have full support for older versions of IE.

The 1.9 release will also be maintained with bugfixes on an ongoing basis. Because jQuery is largely mature and feature complete, the developers believe that 1.9 and 2.0 will remain aligned for the foreseeable future.

Developers who don’t need legacy IE support will be able to use 2.0 and benefit from a faster implementation that doesn’t have to rely on legacy compatibility hacks. Users who need support for older versions of Internet Explorer can continue using 1.9. It will also be possible to use IE conditional comments to ensure that 1.9 is only served to users who actually need it.

The jQuery project’s pragmatic approach to phasing out legacy IE support will serve the needs of Web developers and end users. But it also illuminates the challenges that can arise from having to support old versions of Microsoft’s Web browser.