A smiley face rendered in SVG uses D3.js to demonstrate fundamental DOM manipulation and animation. The code builds the face from primitive shapes—a yellow circle for the head, black circles for the eyes, a path for the mouth—and positions them via group transforms. Two animated eyebrows, implemented as rectangles, shift vertically using chained `transition() .duration(2000)` calls. The example reads SVG dimensions with `parseFloat`, uses helper methods like `select`, `append`, and `attr`, and draws the mouth with the `arc()` shape generator from D3's shape module.