A D3.js smiley face demonstrates animated SVG construction, with eyebrows that repeatedly translate upward and back over two-second transitions. The example builds the face from geometric primitives—circles, rectangles, and an arc path for the mouth—using d3.select to target the SVG element and d3.arc to define the mouth’s curved shape. The code explicitly manages a group hierarchy, translating components like eyes and eyebrows relative to the face’s center. This serves as a foundational exercise in DOM manipulation and chained transition methods within the D3 v5 API.