A smiley face rendered in SVG responds to mouse movement by shifting its eyebrows, demonstrating fundamental DOM manipulation with D3.js. The example uses D3 v5’s `select` method to target the SVG element and the `arc` generator to draw the face’s curved features, such as the mouth. The visualization shows how D3 binds data to existing DOM nodes without requiring `.enter()` or `.append()`, focusing instead on updating attributes in response to user interaction. The face is built entirely through SVG shapes, with styling handled by an external CSS file.