This example demonstrates how to integrate D3 data-loading utilities with React state management. The App component uses React’s `useState` and `useEffect` hooks to asynchronously fetch a CSV file of 1880 baby names via `d3.csv`, then stores the parsed result in component state. While the data loads, a “loading…” message appears; once loaded, the `message` utility computes and displays the file size in kilobytes using `d3.csvFormat`. The visualization itself is minimal, focusing on the data-fetching pattern rather than graphical output.