This example shows a simple yellow smiley face rendered as SVG inside a React component, with a circular head, two eyes, and an arc-shaped mouth. It demonstrates how to integrate D3’s `arc()` generator with React by computing the mouth path’s `d` attribute from angular values. The code uses React 16.9 for component structure, D3 v5 for the arc geometry, and renders everything through ReactDOM into a full-viewport SVG with fixed dimensions of 960 by 500 pixels.