This example uses D3.js to construct an animated smiley face from basic SVG shapes—a yellow circle for the head, separate circles for the eyes, rectangles for eyebrows, and a curved arc for the mouth. The eyes and mouth are static, while the eyebrows perform a looping transition that moves them up and down over two seconds each way. The code demonstrates fundamental DOM manipulation with `d3.select` and `d3.append`, and uses `d3.arc` to generate the mouth’s path, with `transition().duration()` controlling the animation.