CanvasLoader is a web application/UI library for creating canvas preloaders.

CanvasLoader uses HTML5′s canvas element to create awesome spinner preloaders you can later download in .html format.

Of course, canvas animations have a serious drawback — they are only supported if the browser is somewhat up to date.

However, the library does save quite a lot of space for mobile projects.

• Website: http://heartcode.robertpataki.com/canvasloader/

Supplement.js is a small JavaScript library for adding extensions to built-in types.

The library currently extends arrays, functions, numbers and objects.

Supplement.js has some marvelous features that would probably lose a good few work hours when solved individually.

For example, you can remove duplicates from arrays; wrap them; create single-use functions and so much more with this nice library.

• Website: http://supplementjs.com/

markItUp! is a jQuery plugin for turning any text-are into a full blown markup editor.

Its main advantage over other markup editors is its flexibility; whereas you couldn’t make a custom editor out of TinyMCE (well, not an editor that would be easy to update), markItUp allows for endless customization.

There is a number of interesting features that markItUp! has:

• Keyboard shortcut support;
• Easy integration;
• Customizable skins and Ajax previews.

• Website: http://markitup.jaysalvat.com/home/

Stream.js is a JavaScript library for making streams – data structures that, theoretically, can contain infinite amounts of data.

Streams are array-like data that can hold values with, e.g., no upper limit; again, theoretically, this means that it can hold infinite numbers.

Streams aren’t anything new to those with a functional programming background — stream-like data exists in Python and numerous other languages, known as ‘generators’ there.

• Website: http://streamjs.org/

Ender is a open submodule library, operating under Node.js and NPM.

In just 8kb, Ender (or its submodules) manages to deliver an enormous amount of functionality, e.g., a powerful class system, an element animator and a selector engine.

The projects you can make with Ender range from web prototypes to full-blown apps with thousands of users.

• Website: http://ender.no.de/

JointJS is a JavaScript library for creating interactive diagrams.

Although not as groundbreaking as other diagram libraries (like the ascii-to-diagram library ditaa), JointJS provides an extensible way of creating interactive diagrams.

JointJS provides a number of built-in diagram types like hierarchical,  ERD, Org chart, UML, etc.

As JointJS supports JSON, you are able to create full-blown applications — diagramming tools, collaborative diagrams, etc — with it.

• Website: http://www.jointjs.com/
• Demo: http://www.jointjs.com/demos.html