Flotr2 is a library for drawing HTML5 charts and graphs. It is a branch of flotr which removes the Prototype dependency and includes many improvements.

MIDI.js (on github) ties together, and builds upon frameworks that bring MIDI generation to the browser. Combine it with jasmid to create a web-radio MIDI stream similar to this demo... or with Three.js, Sparks.js, or GLSL to create Audio/visual experiments. Piano/guitar simulations, Drum machines, MIDI recording, and all kinds of certified funkitude is within your grasps!

jQuery.validVal is a plugin designed to simplify form validation.
It is highly customizable, very feature rich and can easily be dropped on any type of HTML-form (even AJAX- and HTML5-forms) with very little effort.

In one word: automation. The less work you have to do when performing repetitive tasks like minification, compilation, unit testing, linting, etc, the easier your job becomes. After you've configured it, a task runner can do most of that mundane work for you—and your team—with basically zero effort.

JQuery framework for data visualisation

Leaflet is a modern open-source JavaScript library for mobile-friendly interactive maps. It is developed by Vladimir Agafonkin with a team of dedicated contributors. Weighing just about 28 KB of JS code, it has all the features most developers ever need for online maps.

Infinite scroll has been called autopagerize, unpaginate, endless pages. But essentially it is pre-fetching content from a subsequent page and adding it directly to the user’s current page.

Get the total character/word count of a document

audio.js is a drop-in javascript library that allows HTML5’s tag to be used anywhere.

Sublime-surround is a SublimeText 2 plugin for adding, deleting and modifying text around the cursor or selection.

A polyfill, or polyfiller, is a piece of code (or plugin) that provides the technology that you, the developer, expect the browser to provide natively. Flattening the API landscape if you will.

An interactive widget for trying out regular expressions for JavaScript, and other languages (such as Sed, Ruby, or Perl). It has a simple user interface, case insensitive switch, global switch, and match index array view.

This interactive documentation illustrates the most important features of the Jade templating language. You can play around with the examples and watch the html output in real time.

JsFormat is a javascipt formatting plugin for Sublime Text 2. It uses the commandline/python-module javascript formatter from http://jsbeautifier.org/ to format the selected text, or the entire file if there is no selection. The plugin does not check to make sure the buffer has a ".js" file type, it just javascript formats the selection/file. Thus, use with caution if you are in an html file.

Trends in web technology - load times, download sizes, performance scores;
Interesting stats - popular scripts, image formats, errors, redirects;
Website performance - specific URL screenshots, waterfall charts, HTTP headers.

Chained is simple jQuery plugin for chained selects. You can choose from two different versions. Use jquery.chained.js if you do not want to make external queries for setting content of child selects. This version uses classnames of select options to decide content. As a bonus it is usable even with JavaScript disabled. However with JavaScript disabled there is one catch, all options will be shown to user.

Backbone.js gives structure to web applications by providing models with key-value binding and custom events, collections with a rich API of enumerable functions, views with declarative event handling, and connects it all to your existing API over a RESTful JSON interface.

Fresco is a beautiful responsive lightbox. It can be used to create stunning overlays that work great at any screen size, in all browsers on every device.

Zepto is a minimalist JavaScript library for modern browsers with a largely jQuery-compatible API. If you use jQuery, you already know how to use Zepto.

CSS, PHP and JavaScript completions for Sublime Text 2.