This example combines React and D3 v7 to create a smiley face whose eyes jitter randomly on each render. The face is drawn with SVG primitives, including a linear gradient for the face, and D3’s `arc` API generates the mouth path. React components compose the face, eyes, and mouth, while `useState` and `useCallback` track mouse movement to position a separate outline circle, demonstrating interactive SVG rendering in a React framework. The source data is entirely procedural, with no external data loading.