skrollr is a standalone, zero-dependency JavaScript library for creating parallax scrolling effects and scroll-driven animations. It operates by reading HTML5 `data-` attributes on elements to define keyframes (sets of CSS property values) at specific scroll positions, then interpolates between them as the user scrolls. The library supports both absolute mode (keyframes tied to document scroll offset) and relative mode (keyframes triggered by element position relative to the viewport), along with per-property easing functions, constants, and percentage-based offsets. It handles vendor prefixes automatically and includes a custom mobile mode that replaces native scrolling with CSS transforms for touch devices. The core rendering loop uses requestAnimationFrame, and the library exposes a clean public API for programmatic control (scroll, animate, refresh, destroy). Despite being feature-rich and well-documented, the codebase has not been actively maintained since 2014, relies on outdated build tools (Grunt, Node 0.10), and contains legacy patterns (e.g., user-agent sniffing for mobile detection). Its architecture is a single-file singleton with internal state, making it straightforward to use but harder to integrate with modern module systems without the provided AMD/CommonJS shims.