A smiley face rendered in SVG demonstrates basic D3.js DOM manipulation, with animated eyebrows that move to change the expression. The example uses D3 v5's `select` and `arc` functions to construct the facial features, building circles and arcs for the eyes, mouth, and brows within an SVG canvas. The code shows how D3 can directly create and update SVG elements through its data-binding and selection APIs, while the accompanying stylesheet hides page overflow for a clean, focused presentation.