This example shows a grid of 40 by 60 red squares arranged across an SVG canvas, with each square’s width and height varying according to the cosine of its row index, creating a wave-like pattern of alternating sizes. The code uses React to render the SVG elements, with ReactDOM mounting the App component into the page. D3’s `range` function generates the row and column coordinates, while custom `makeSquare` functions produce the rectangles. The visualization demonstrates how React and D3 can be combined to generate dynamic, data-driven SVG layouts.