This example shows a modular smiley face built with React and D3, rendered as SVG. It separates the face into reusable components: a yellow background circle, two eyes, and a mouth drawn with D3's `arc` generator. The components are positioned using SVG `<g>` transforms for translation. The code uses D3 v7's `arc()` function to create the mouth path and React 17 for component composition, with `ReactDOM.render` mounting the app to the root element.