Buster
A powerful suite of automated test tools for JavaScript.
Bootstrap Ajax
A library for adding declarative ajax functionality to your website
101
A modern JS utility library
Sentry
Sentry is a realtime error logging and aggregation platform
Platform.js
A platform detection library that works on nearly all JavaScript platforms.
Oc Lazy Load
Load modules on demand (lazy load) in AngularJS
Mobx
Simple, scalable state management.
Px Loader
PxLoader is a simple JavasScript library for creating preloaders and resource downloaders for HTML5 apps.
Canjs
Can do JS, better, faster, easier.
Theory
Abstraction layer for cross platform JavaScript.
Tweet
put twitter on your website with tweet, an unobtrusive javascript plugin for jquery
Mobservable
Observable data. Reactive functions. Simple code.
Joosy
Joosy is a browser applications framework. That is based on Rails, CoffeeScript and love.
JayData
JayData is a unified data access library for JavaScript to CRUD data from different sources like WebSQL/SQLite, IndexedDB, MongoDb, ASP.NET WebAPI, OData, HTML5 localStorage, Facebook or YQL. The library can be integrated with KendoUI, Knockout.js, Handlebars.js or Sencha Touch 2 and can be used on Node.js as well.
Gijgo
Gijgo - Free Javascript Controls
Optics
Profunctor implementation of Lenses, Prisms, Traversals, Isos, etc.
Highway
A fast, lightweight and simple Javascript routing library with no dependencies.