Lazy.js
Like underscore.js, but lazier
Refluxjs
A simple library for uni-directional dataflow application architecture inspired by ReactJS Flux
Firebase Js Sdk
Firebase Javascript SDK
Xsm
State Management made eXtraordinarily simple and effective for Angular, React, and Vue
Invisible
Invisible.js: Reusable models for the client and the server
Venus.js
where bugs go to die
Serenade.js
Client side MVC framework
Mediator.js
An implementation of the mediator pattern for asynchronous events in Javascript
Cellx
Ultra-fast implementation of reactivity for javascript
Then.js
The fastest, smallest, fully compatible, full-featured asynchronous module!
Nanobar
Very lightweight progress bars. No jQuery
Delorean
An Agnostic, Complete Flux Architecture Framework
Backbone Nested
A plugin to make Backbone.js keep track of nested attributes.
Pilot
Pilot — multifunction JavaScript router.
Thinkjs
Use full ES2015+ features to develop Node.js applications, Support TypeScript.
Knockout
Knockout makes it easier to create rich, responsive UIs with JavaScript