This example demonstrates an interactive circle that follows the mouse pointer across an SVG canvas in a React application. The circle’s center coordinates update dynamically based on cursor position, handled through React state and the `onMouseMove` event. The code uses React 16.13.1 with `React.useState` and `React.useCallback`, rendering to the DOM via `ReactDOM.render`. No external data is loaded; the visualization relies solely on user input to drive the black circle’s movement within a 960x500 viewport.