This example shows a diagonal series of four blue ellipses positioned incrementally across an SVG canvas. The code selects the body element, appends an SVG container with fixed width and height, and binds an array of ellipse objects containing center coordinates and radii. Using D3 v4’s data join, it creates each ellipse via `selectAll("ellipse").data().enter().append("ellipse")`, then sets the `cx`, `cy`, `rx`, and `ry` attributes from the bound data. A CSS filter targets the first child ellipse to apply a blue fill.