SmartUnderline is an open-source JavaScript library which uses clever tricks to draw underlines in a more beautiful and readable way.

We've not yet put this into a project, but its effect is very pretty. Please update this card when you use it.

Insanely detailled guide about controlling copy & paste behavior using web technology in 2015.

Note that you can now trigger a copy action through Javascript, no Flash required.

Build dashboards using ascii/ansi art and javascript

Awesome!

Responsive Lightbox JavaScript that just works.

You can use it for single images or a gallery. Animations are optional.

Databound provides Javascript a simple API to the Ruby on Rails CRUD.

Tries to expose a full model CRUD as an API. Not sure if this is useful for more refined requirements.

Create beautiful Javascript charts with one line of Ruby.

Promising chart library for easily rendering charts with Google Charts.

This seems to not submit your data points to Google.

RulersGuides.js is a Javascript library which enables Photoshop-like rulers and guides interface on a web page

Also available as a bookmarklet.

Clever hack to allow user interaction without Javascript (by using radio buttons and selecting on :checked).

Opal is a source to source ruby to javascript compiler, corelib and a runtime implementation that currently passes 3000 rubyspecs w/a reachable goal of passing them all.

Tracekit is a JavaScript library that automatically normalizes and exposes stack traces for unhandled exceptions across the 5 major browsers: IE, Firefox, Chrome, Safari, and Opera.

Shows how to implement an animated progress bar in pure CSS, without animated GIFs, Javascript or Flash.

Makes a robust determination of a user's timezone through Javascript.

Interesting interview with DHH, where he talks about how they made the new Basecamp feel very fast without using a lot of Javascript (most of Basecamp still lives on the server). The two tricks they used are PJAX and Russian Doll Caching.

TagCanvas is a Javascript class which will draw and animate a HTML5 canvas based tag cloud.

A small library to provide the Rails I18n translations in Javascript clients.

CodeMirror is a JavaScript component that provides a code editor in the browser. When a mode is available for the language you are coding in, it will color your code, and optionally help with indentation.

Chrome now supports desktop notifications using WebKit's webkitNotifications API. This means you can create popup bubbles from Javascript.

jQuery as new default Javascript library, streaming response support, attr_accessible with roles, prepared statements, easier migrations.

Free Hoptoad/Airbrake alternative which can capture exceptions from any platform. It comes with a Rails notifier and a RESTful API to write your own notifiers for Javascript, etc.

Should we some day wish to do away with the current way we deal with exceptions, this might be a good place to start.

Liquid Canvas is a JavaScript library which allows you to draw inside an HTML canvas element with an easy yet powerful description language.

It can be used to add graphics to your web page without ever touching an image creation tool such as The Gimp, Inkscape or Photoshop.

Check out the Demo and the basic example and then download version 0.3.

Terminus is a Capybara driver where most of the driver functions are implemented in client-side JavaScript. It lets you script any browser on any machine using the Capybara API, without any browser plugins or extensions.

Reads Active Record's validations and makes them available to live client side javascript

A Rails plugin that delivers a special message to DiggBar users, or runs frame-killer javascript.

As a Typekit user, you’ll have access to our library of high-quality fonts. Just add a line of JavaScript to your markup, tell us what fonts you want to use, and then craft your pages the way you always have. Except now you’ll be able to use real fonts.