Clusterize.js is a tiny vanilla JS plugin to display large data sets easily.
Wraith is a screenshot comparison tool, created by developers at BBC News.Wraith uses a headless browser to create screenshots of webpages on different environments (or at different moments in time) and then creates a diff of the two images; the affected areas are highlighted in blue.
An off-canvas sidebar component with a collection of animations and styles using CSS transitions.
StackEdit is a full-featured, open-source Markdown editor based on PageDown, the Markdown library used by Stack Overflow and the other Stack Exchange sites.
Laroux.js is a jQuery substitute for modern browsers and mobile devices. But instead of offering some wrappers and own dynamics, it simply provides helper functions to achieve the same objectives as jQuery or Zepto.