Zepto.js is a minimalist JavaScript framework for modern browsers, with a jQuery-compatible syntax.
From the project-site: http://zeptojs.com/
"Zepto is a minimalist JavaScript library for modern browsers with a largely jQuery-compatible API. If you use jQuery, you already know how to use Zepto.
While 100% jQuery coverage is not a design goal, the APIs provided match their jQuery counterparts. The ultimate goal is to have a ~5-10k library that downloads and executes fast, with a familiar and versatile API, so you can concentrate on getting stuff done."
Source code: https://github.com/madrobby/zepto