This example demonstrates basic DOM manipulation with D3.js by constructing a smiling face from SVG primitives and animating its eyebrows. Built with D3 v5, the code uses the `select` API to target the SVG element and `append` to create circles, rectangles, and a path for the mouth. The eyebrows are animated using chained `transition().duration()` calls, moving them vertically over two seconds before returning to their original position, with the mouth drawn via D3's `arc` function to create a crescent shape.