This example creates 50 randomly sized and positioned circles on an SVG canvas using D3 v5 and React 16 hooks. The circles bounce horizontally across the screen via a `d3.timer` callback that updates their `cx` attributes each frame. A button labeled "Sort" reorders the circles by descending radius using a JavaScript state update, while a "Revert" button randomizes their positions again. It demonstrates integrating D3 selections with React's `useState` and `useEffect` for managing dynamic visual state.