Let's make a face with D3.js!
D3.js draws a yellow smiley face as a scalable SVG, centered in a 960×500 canvas. The face’s circular head, eyes, eyebrows, and arcing mouth are built by appending SVG primitives—`circle`, `rect`, and `path`—to a group. The example demonstrates core DOM manipulation with `d3.select` and `append`, while a chained `transition().duration(2000)` sequence animates the eyebrows, moving them up and down over four seconds. The mouth uses the `d3.arc` shape generator with specified inner and outer radii and angle ranges.