This work overlays two sets of horizontal and vertical bars, each with the same SVG mask, to create a circular window that reveals the bar pattern inside a defined radius. The code uses D3 version 6.6.1, specifically the `select`, `range`, and `join` APIs, to append SVG rectangles and define two masks with a circle. The visualization is rendered in SVG, with the bars drawn across the full width or height, and the masks configured to hide or show content within the circle.