A D3.js smiley face animates by moving its eyebrows up and down in a looping transition. The face is built entirely with SVG primitives—circles for the eyes, rectangles for the eyebrows, and an arc-generated path for the mouth—positioned within a centered group. Using `d3.select`, `d3.arc`, and chained `transition().duration()` calls, the code shifts the eyebrow group’s vertical translation between two offsets. A black background and yellow face with black strokes create clear visual contrast. The example demonstrates fundamental DOM manipulation and SVG rendering with D3 v5.