jQuery 2 has been released and the most talked about addition is actually the removal of a feature. Notably, support for Internet Explorer versions 6, 7 and 8. The jQuery blog notes that Android 2.x browsers are the next on the chopping block. You may think that the new features in jQuery 2.0 would have to be substantial to encourage developers to use it and leave IE 8 behind, but at this point the APIs of jQuery 1.9 and 2.0 are identical. In other words, they provide the exact same set of features, they just support different browsers. In addition, both the 1.x and 2.x versions of jQuery will continue to be supported side-by-side for the foreseeable future. jQuery 1.10 is will be released in the coming months with bug fixes from the 2.0 cycle.
<!--[if lt IE 9]><!-->
<!--[if gte IE 9]><!-->
The first line checks to see if the requesting browser is lower than IE 9. If it is, then we load jQuery 1.9. The second line checks if it is greater than or equal to IE 9. If it is, then we load jQuery 2.0. Since the 1.9 and 2.0 APIs are identical, the rest of the calls to jQuery on the page will work properly with no additional changes required. Take note that there are some additional comment tags included to make these checks visible to non-IE browsers such as Chrome or Firefox.
Many developers considered jQuery’s support for a wide range of browsers to be a significant benefit for choosing it over other alternatives. Often a project’s targeted audience or the client themselves will determine what browsers need to be supported, leaving the developer out of the decision entirely. With the newest version shifting from that support, the door may be left open for a competitor product to gain usage in the developer community. At this point, there is no cause for alarm since the jQuery 1.x line will continue to be supported in the future. However, if jQuery 2.0 begins to add features that are not available in 1, developers may demand a version of jQuery 2 with support for older browsers, or just move on to something new. Only time will tell.