Thinkjs
Use full ES2015+ features to develop Node.js applications, Support TypeScript.
Tempo
Tempo is an easy, intuitive JavaScript rendering engine that enables you to craft data templates in pure HTML.
Refluxjs
A simple library for uni-directional dataflow application architecture inspired by ReactJS Flux
Durandal
A cross-device, cross-platform client framework written in JavaScript and designed to make building Single Page Applications (SPAs) easy to create and maintain.
Boiler
Boiler is a utility library that makes every day tasks in JavaScript easier by providing over 115 methods that work on arrays, collections, functions, numbers, objects, and strings.
Nunjucks
A jinja2-inspired templating system for javascript
Machina.js
js ex machina - finite state machines in JavaScript
Stampit
Create objects from reusable, composable behaviors.
Bacon.js
FRP (functional reactive programming) library for Javascript
Lunr.js
A bit like Solr, but much smaller and not as bright
Impress
Impressive totalitarian style Multipurpose Application Server for node.js. All decisions are made. Solutions are scaled. Tools are provided and optimized for high load. Ready for applied development and production.
Fast.js
Faster user-land reimplementations for several common builtin native JavaScript functions.
Backbone.stickit
Backbone data binding, model binding plugin. The real logic-less templates.
Lucid Js
LucidJS is a chainable event emitter library. It offers several unique features such as set events, emitter piping, DOM node encapsulation, sub events, along with the usual event triggering and binding. LucidJS emitters also feature meta events that allow listening for event binding and event triggering. LucidJS works in both the browser and node.js.
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.
Conditioner
Frizz Free, Environment-aware, JavaScript Modules
JS Signals
Custom Event/Messaging system for JavaScript inspired by AS3-Signals