Fork of Circles with D3.
This example demonstrates how to create and position seven filled circles within an SVG element using D3.js v7, with each circle’s coordinates, radius, and color defined in a plain JavaScript data array. The visualization initializes a single SVG that adapts to its container’s dimensions, then applies the D3 general update pattern via `select`, `data`, and `join` to bind the array to circle elements. Method chaining sets the `cx`, `cy`, `r`, and `fill` attributes for each circle, while a shared opacity value adds visual layering.