js ajax library,javascript - Lightweight JS AJAX library - Stack Overflow

The selector portion of jQuery, dojo (and some of the other frameworks) is actually available as a separate library, the Sizzle Selector library:

Sizzle purports to be only 4kb minified and gzipped according to their site.

However, with ajax too, I think a customized jquery with only the smallest bits may be the best "complete package". Some of the other libraries like dojo have methods of building them with exactly the features you want, too.

The default jquery minified+gzipped is only 19kb. I think a core build can be done down to only 12kb.