This example uses JavaScript and the SVG API to construct a full-screen pattern of thin vertical and horizontal rectangles. It defines two SVG groups, each masked by a circle: one group displays vertical lines, the other horizontal lines, with the masks being inverses of each other. The resulting visualization shows a grid of perpendicular lines, with a circular region in the center showing only vertical lines, while the surrounding area displays only horizontal lines. The code programmatically creates SVG elements, including masks and groups, without using any external visualization libraries.