A smiling face built with D3.js v6 renders as an SVG with animated eyebrows. The code uses `d3.arc` to draw the mouth and `d3.select` to append circles, rectangles, and a path for facial features. Eyebrows transition vertically in a looping sequence via `transition.attr` and an `on('end')` callback. All geometry is centered by translating a group element, and dimensions are derived from the SVG’s width and height attributes.