跑到jQuery官网看了一下原来jQuery2.x不支持IE678
jQuery 2.x
jQuery 2.x has the same API as jQuery 1.x, but does not support Internet Explorer 6, 7, or 8. All the notes in the jQuery 1.9 Upgrade Guideapply here as well. Since IE 8 is still relatively common, we recommend using the 1.x version unless you are certain no IE 6/7/8 users are visiting the site. Please read the 2.0 release notes carefully.