A D3.js animation displays a yellow smiley face with black eyes and a curved mouth on a plain SVG canvas. The code uses `d3.select` and `d3.append` to construct the face from circles, a path, and rectangles. Eyebrows animate vertically via chained `transition().duration(2000)` calls, moving up and down repeatedly. The example demonstrates fundamental DOM manipulation and SVG attribute updates within the D3 v5 framework, using `arc()` for the mouth path.