This example shows a collection of colored circles rendered in an SVG canvas using a React component and D3.js. The visualization maps data from a static array of objects, each containing x- and y-coordinates, radius, and a hex color value. The React component uses a `useRef` hook and `useEffect` to pass the SVG selection to a D3 `select` call, which binds the data and joins circle elements. The rendering relies on D3's data join pattern and React 19's `createRoot` for mounting.