Marilyn
Marilyn is a client side, Socket.IO driven, Pub/Sub, model layer with a query system similar to Mongoose.
Sortable
Sortable — is a minimalist JavaScript library for reorderable drag-and-drop lists on modern browsers and touch devices. No jQuery. Supports Meteor, AngularJS, React and any CSS library, e.g. Bootstrap.
Zangodb
MongoDB-like interface for HTML5 IndexedDB
Plottable
A library of modular chart components, built on D3
Collections
This package contains JavaScript implementations of common data structures with idiomatic interfaces.
Js Store
JsStore is an IndexedDB Wrapper. It makes IndexedDB super easy with its SQL like apis.
Officegen
Standalone Office Open XML files (Microsoft Office 2007 and later) generator for Word (docx), PowerPoint (pptx) and Excell (xlsx) in javascript. The output is a stream.
Flotr2
Graphs and Charts for Canvas in JavaScript.
Morris.js
Pretty time-series line graphs
Faye
Simple pub/sub messaging for the web
Uv Charts
Simple yet powerful JavaScript Charting library built using d3.js
Brain
[UNMAINTAINED] Neural networks in JavaScript
Jumly
Rendering engine for UML diagrams in JavaScript
Arbor
A graph visualization library using web workers and jQuery
Gpu.js
GPU Accelerated JavaScript
Local Storage
A localStorage polyfill
Backgrid
Finally, an easily stylable semantic HTML data grid widget with a Javascript API that doesn't suck.