There are countless popular JavaScript libraries, such as jQuery, MooTools, Prototype, Dojo, and YUI. These JavaScript libraries are feature-rich, and with their plugins, they can almost handle any task. However, this comes at a cost, as these libraries often bloat the size of your webpages. In some cases, if you only want to accomplish specific tasks, you can use some more specialized and lightweight libraries. This article introduces 40 exceptionally great lightweight JavaScript libraries. This is the second part of the article; for the first part, see 40 Lightweight JavaScript Libraries (Part 1).