Paper.js is an open source vector graphics scripting framework that runs on top of the HTML5 Canvas. It offers a clean Scene Graph / Document Object Model and a lot of powerful functionality to create and work with vector graphics and bezier curves, all neatly wrapped up in a well designed, consistent and clean programming interface.
On the project website, there are some examples of using. For each example, the source code is available and editable online. The library is also well documented, many tutorials allow everyone to understand how Paper.js works.
Introducing Jürg Lehni
Jürg Lehni (born in 1978 in Lucerne, lives and works in London) is an independent designer, developer and artist. His work relates to a reflection on computers, its uses and adaptations that technology demand. He was made famous by his diploma project at ECAL in 2002: Hektor. Hektor is a kind of robot / paint spraying device, it's a portable object assisted by computer. According to Jurg Lehni, it's essential to open, in the field of aesthetics, new spaces of action, which machines and existing software can't access. That's why Jürg Lehni created his tools. He also contributes to the to the improvement or development of open source tools for artists or designers, like the Adobe Illustrator plugin: Scriptographer.Tool creation / increment, Document sharing, Source sharing