A smiley face drawn with D3.js animates its eyebrows in a repeating up-and-down motion, created by transitioning the group element that contains both eyebrow rectangles. The face is built entirely with SVG shapes, including circles for the eyes and an arc for the mouth, using D3 selections and the `d3.arc` function. The animation runs via chained `transition().duration(2000)` calls, which move the eyebrows up and then back to their original position.