This example demonstrates fundamental DOM manipulation with D3.js by constructing a smiley face from SVG primitives—a yellow circle, two eyes, eyebrows, and a mouth—and animating the eyebrows through a two-stage transition. The code uses D3 v5’s `select`, `append`, and `attr` methods to build the SVG structure, while the `transition().duration(2000)` API moves the eyebrow group vertically in a looping sequence. The mouth is drawn with the `arc` shape generator, and static layout parameters such as `eyeSpacing` and `eyebrowYOffset` control facial proportions.