- jQuery 2 will no longer support old Internet Explorer 6, 7, and 8, which will make the library significantly faster to run for web applications. Internet Explorer 9, since it is rewritten to support modern web standards, will be supported.
- jQuery 1.9 will be feature-compatible (i.e., API compatible) with jQuery 2 and support old Internet Explorer 6, 7, and 8. It will be significantly slower because it provides workarounds for problems in old Internet Explorer.
- Web developers will include a HTML conditional comment to swap between using jQuery 1.9 for old Internet Explorer and jQuery 2 for modern web browsers, including Chrome, Firefox, Safari, and IE 9.
For more information about the recent developments of jQuery, refer to: