Fork of Let's make a face with D3.js!
A smiley face drawn with D3.js animates its eyebrows in a repeated rise-and-fall motion. The example demonstrates fundamental DOM manipulation by building the face from SVG elements—circles for the eyes, rectangles for the eyebrows, and a path generated with the `d3.arc` helper for the mouth. Eyebrow movement uses chained `transition().duration()` calls to shift the group’s `transform` attribute, alternating between raised and lowered positions. The code imports `select` and `arc` from D3 v5 and renders entirely in SVG on a 960×500 canvas.