React
React is a JavaScript library for building user interfaces.
Angular.js
AngularJS lets you write client-side web applications as if you had a smarter browser. It lets use good old HTML (or HAML, Jade and friends!) as your template language and lets you extend HTML’s syntax to express your application’s components clearly and succinctly
Ionic
Advanced HTML5 Mobile App Framework. A beautiful front-end framework for developing hybrid mobile apps in HTML5. Best friends with AngularJS.
Vue
Intuitive, fast & composable MVVM for building interactive interfaces.
Redux
Predictable state container for JavaScript apps
Moment
Parse, validate, manipulate, and display dates in javascript.
Chart.js
Simple HTML5 Charts using the <canvas> tag
Ember
Ember.js is a JavaScript framework that does all of the heavy lifting that you'd normally have to do by hand. There are tasks that are common to every web app; Ember.js does those things for you, so you can focus on building killer features and UI.
Three.js
JavaScript 3D library.
Babel
Babel is a compiler for writing next generation JavaScript.
6to5
Turn ES6 code into readable vanilla ES5 with source maps
Meteor
Meteor, an ultra-simple, database-everywhere, data-on-the-wire, pure-Javascript web framework.
Foundation
The most advanced responsive front-end framework in the world. Quickly create prototypes and production code for sites and apps that work on any kind of device.
Leaflet
JavaScript library for mobile-friendly interactive maps
Socket.io
Realtime application framework for Node.JS, with HTML5 WebSockets and cross-browser fallbacks support.
Webpack
Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jade, coffee, css, less, ... and your custom stuff.