This example demonstrates fundamental DOM manipulation with D3.js by constructing an interactive smiley face with moving eyebrows. It uses D3 selections to create SVG elements and animate eyebrow positions. The code relies on D3 v5’s core API, including `d3.select`, `d3.append`, and `d3.interval` for real-time updates, while styling is handled via external CSS. The page renders a blank body and injects elements dynamically, showcasing basic data-driven document manipulation without external datasets.