Let's make a face with D3.js!
This example uses D3.js version 5 to construct a yellow smiley face with eyes, eyebrows, and a mouth directly in an SVG. It demonstrates fundamental DOM manipulation by selecting elements, appending shapes, and applying attributes. The code uses `d3.select` and `d3.arc` to generate the mouth path, while a two-stage `transition()` chain animates the eyebrows upward and then back to their original position over 4 seconds.