Last checked and updated on 30 May 2026
What Is New in jQuery 2 (summary table)
jQuery 2.x is a slimmer, faster version of the library that shares an API with jQuery 1.x but removes support for older Internet Explorer versions (6, 7, and 8). This allows for a significantly reduced codebase and performance improvements.
| Category | Key Changes in jQuery 2.x |
|---|---|
| Browser Support | Dropped support for Internet Explorer 6, 7, and 8. Targets modern browsers and IE9+. |
| Size & Performance | Smaller file size and performance gains across common operations due to removed legacy IE code paths. |
| API & Features | Maintains identical API to jQuery 1.9+. Some deprecated code from earlier 1.x versions was removed. |
| Release Model | Parallel releases with the 1.x branch, allowing developers to choose between IE8 support (1.x) or a leaner build (2.x). |
Why Did jQuery 2 Drop Support for Old Internet Explorer?
The primary goal was to remove the large volume of code specifically written to handle bugs and missing features in IE6, 7, and 8. This code was a major source of complexity and file size bloat. By cutting it, the library became smaller and faster for the vast majority of users on modern browsers.
In practice, this meant the development team could optimize for web standards without maintaining workarounds for decade-old browsers. The shared API with the 1.x line meant you could switch versions without rewriting your application logic, only your browser support policy.
What Performance Gains Came from Removing Old IE Code?
Performance improvements weren't from rewriting core algorithms, but from deleting entire execution paths. Functions no longer needed to check for IE8's broken box model or attach data via proprietary APIs. Every DOM manipulation, event handler, and AJAX call became slightly more efficient by shedding this baggage.
Subsequent 2.x releases, like 2.2, continued to refine performance. For example, the .css() method and offset calculation saw measurable speedups. These micro-optimizations added up, especially in complex, interactive applications.
How Did the jQuery 2.x and 1.x Release Lines Coexist?
jQuery adopted a parallel release strategy. The 1.x branch continued to support IE8 and received bug fixes and minor updates. The 2.x branch, sharing the same API, was for projects that could abandon IE8. This let teams pick a version based on their support requirements, not different feature sets.
Both lines were developed simultaneously. A fix for a modern browser bug in 2.2 would also be ported to 1.12. This ensured the only difference was legacy IE support, making the choice straightforward for developers.
FAQ
Should I upgrade my existing project from jQuery 1.x to 2.x?
Only if you are certain your users do not require Internet Explorer 8 or lower support. The APIs are the same, but the removal of IE6-8 code in 2.x will break functionality for those browsers.
Can I use a plugin written for jQuery 1.9 with jQuery 2.0?
Yes. Since jQuery 2.0 maintains API compatibility with jQuery 1.9 and above, most plugins will work. The exception would be a plugin that specifically depends on IE8-or-lower behavior that was removed.
Is jQuery 2.x faster than 1.x in all browsers?
It's faster in browsers that never needed the legacy IE code, like Chrome, Firefox, and IE9+. In IE8 itself, jQuery 2.x does not run at all, so you must use the 1.x line for that environment.
What happens if a user with IE8 visits a site using jQuery 2?
The browser will likely fail to parse the JavaScript file, and any jQuery functionality will be completely broken. You must use feature detection or conditional comments to serve jQuery 1.x to those browsers.
Were any features added in jQuery 2.2 that aren't in 1.12?
No. jQuery 2.2 and 1.12 were released together with the same set of bug fixes and improvements for their respective browser support profiles. New features were not the focus; parity and stability were.