A yellow smiley face with moving eyebrows demonstrates fundamental DOM manipulation and animation with D3.js. The code selects an SVG element and builds the face using circles for eyes, rectangles for eyebrows, and a d3.arc path for the mouth. A chained transition on the eyebrows group animates its vertical position over two seconds, then returns it, creating a repetitive raising and lowering effect. The example relies on D3 v5 selections, attributes, and transitions in a straightforward SVG scene.